Power Grid Freq Variations To Be Allowed

[HeyBub]

And if you'd said: "In thirty minutes it'll be a quarter to twelve"?

[larry moe 'n curly]

Dad built one of these kits in the early 1970s:

Power outage causes it to display 88:88:88, and it's line locked, no crystal. He said it started to be off by a few seconds a month, starting a couple of years ago, and he suspects the power company.

[krw]

I knew several *engineers* who had the government buy these things for them under the GI bill. They were "studying to become TV repairmen". Right.

Displaying 88:88:88 makes more sense than 12:00:00. Some will then start incrementing - *bad* design.

The power company is likely more accurate than a crystal. The cumulative error over a long period (month) should be zero. The error could also be the zero-crossing detector getting noisy. Often it'll get much worse.

[The Daring Dufas]

A lot of the test equipment from the big old name brand manufacturers had crystal ovens inside for the time base circuitry when I worked a bench tech in a repair depot 30 years ago. Like gold boat anchors and just as expensive. :-)

TDD

[The Daring Dufas]

Many digital clocks listen to WWV NIST radio stations to set the time. I bought such a clock years ago and just a few years ago I bought an inexpensive Sony clock radio that had the same feature. I'm not sure if it got its time signal from WWV or there is something now being broadcast by radio stations or if it picks it up from a cellphone tower. There seem to be a lot of things sending out time signals. Heck, if I'm remembering right, POTS line caller ID does it too.

TDD

[Paul Hovnanian P.E.]

[snip]

Frequency isn't regulated on a per-plant basis. The system operator will monitor the grid frequency and lead or lag from an ideal 60 Hz cycle count. They will schedule generation to be added or subtracted based on these figures. Unless your plant is intended to run islanded on occasion, such frequency regulation is unneeded.

[Robert Green]

There's a big difference between the phrase "I brought my 45's to school" spoken in 1960 and 2011.

(-:

-- Bobby G.

[krw]

Then there was Russ Meyer in the '70s; forget about 38s, how 'bout her 44s?

[Robert Green]

And they were REAL 44's, not silicone. He did have an eye for the ladies.

-- Bobby G.

[The Daring Dufas]

About 10 years ago, I was at a bowling alley when a little kid about 8-9 years old came up to the counter and asked the clerk if he could use the phone to call home. The clerk reached under the counter, pulled out an old Western Electric rotary dial desk phone and the kid was completely dumbfounded. The kid had no idea how to operate the old telephone. ^_^

TDD

[Bob]

It's gone one step further now with kids and wired phones. Many kids are unfamiliar with aspects of basic wired phones that we take for granted such as taking the receiver off the hook before keying the dialed digits, and placing the receiver back on the hook to end the call. Where's the OFF button?

[The Daring Dufas]

Their kids are going to have tooth implant cellphones and I'm sure one of today's cellphones will be just as archaic to them. ^_^

TDD

[krw]

It took me a lot longer to figure out how to use a cell phone than it did a rotary phone.

[mike]

So, you're saying that an electrical engineer isn't influenced by the same politics that affects non electrical engineers? Don't forget that about half the electrical engineers perform below average ;-)

[mike]

This is one of those cases where statistics mask the issue. When the power goes out, it's obvious. I go around the house fixing all the clocks that are no longer accurate. Life returns to normal.

Not knowing whether the clock on the wall is correct is a much bigger problem. How often do I have to get out the ladder to climb up and reset the clock?

I'll bet there'll be lots of consequences. The clock on my 40-year-old stove will be affected. And I ain't replacing it...EVER. I'll bet there are lots of legacy timepieces used in employee time clocks, old buildings, etc.

The question is not, whether I'm able to find the correct time. The question is, can I get accurate time from every time indicator in view.

Knowing that most newer devices will not be affected is comforting only to those who don't have legacy devices.

[Ivan]

Old saying: A man with a watch knows what time it is. A man with two watches is never quite sure.

[JIMMIE]

That hasn't been an accurate statement for quit some time. Whole clocks can be built for the cost of the circuitry involved of syncing the clock to to the power line. Oscillators built into the clock IC are more than accurate enough to maintain accurate clock time over years. Case in point, my trucks clock, 2003 Nissan bought in fall of

2002. Clock has never been set except by the dealer. It is now about 30 seconds off and it has always been about 30 seconds off per my cellphone clock. I never bother correcting it for DST. The Design of clocks Jonathan is talking about used an RC oscillator that was synced to the power line. By design the oscillator was a little slow, this made syncing it to the power line signal easier. Also have a desk clock meant to run on a aaa or aaaa battery but I now have it wired into 4 D cells in parallel. It has maintained accuracy for years also.

Jimmie

[Peter]

Four devices with digital clocks in my house regularly gain 10-20 seconds/week, even when there are no power outages: (1)2 year old DVR (non-TIVO) connected to an antenna for input (no cable/satellite/FIOS) that has only a 30 second memory in case of power failure (probably a small capacitor), 3 year old microwave oven, (3) 10 year old clock-radio, and (4) 15 year old VCR with a 1 hr. memory in case of power failure. All 4 are on different circuit breakers. I've had our power company check our line for noise, voltage, and/or frequency abnormalities and they found none. 3 other digital clock radios, varying in age from 1-15 years old, some on the same and some on different house circuits keep essentially perfect time. I use timer recording on the VCR and DVR regularly and if I don't reset their clocks weekly, I can lose the end of programs I record unless I always add time at the end. No one has ever proposed an explanation or a serious fix for this situation.

[Mark Lloyd]

[snip]

or like the "cerebrum communicator" in "The Presidents Any list"?

[Mark Lloyd]

[snip]

I've had clocks that do that, and clocks that PRETEND to do that.