AC frequency - does it matter?

[mzeitlin3348]

I have a power meter plugged into my AC mains which shows me among other things, AC frequency, power, voltage, etc.

This morning, I noticed that my line frequency was not a rock solid 60 Hz. Instead it was 59.9 Hz. and stayed that way for about an hour and then bumped up. Don't clocks require a 60Hz signal to maintain accuracy? I also wonder how this happens given the frequency is set at the grid. Just curious

 

[SolderIron]

I am with you on the old style clocks use AC line for time. Not so much on new ones. How stable is your measuring device

 

[mzeitlin3348]

I am with you on the old style clocks use AC line for time. Not so much on new ones. How stable is your measuring device

I read somewhere the total cycles for a given day must not change and that if the line frequency changes during the day, the power company adjusts the cycles so that the day finishes with
5.184 X 10^6 cycles per day. And then starts over. Can someone verify?

https://en.wikipedia.org/wiki/Utility_frequency
(is this true?) - is it only for clocks? or is there a fundamental reason why the power company can not let the total cycles in a day change from day to day.

 

[sregor]

I read somewhere the total cycles for a given day must not change and that if the line frequency changes during the day, the power company adjusts the cycles so that the day finishes with
5.184 X 10^6 cycles per day. And then starts over. Can someone verify?

https://en.wikipedia.org/wiki/Utility_frequency
(is this true?) - is it only for clocks? or is there a fundamental reason why the power company can not let the total cycles in a day change from day to day.

I have heard the same thing. I know of nothing other than clocks or for timing purposes that that kind of accuracy is required. Some turntables (First I heard of was Technics) Have precise speed controls and use internal timers to control the strobes, as it would show the drift in line frequency if it used that for reference) my two cents.....

 

[Hyperion]

I think if the frequency changes slightly then the power consumption of many devices will also change similarly, another reason to keep the daily or longer term average at exactly the line frequency.

 

[Bill Ferris]

 

[gadget73]

Turntables with a synchro motor will be affected, direct drive and other forms of servo control will not be. Would it be enough to really notice? Maybe, maybe not.

 

[Pio1980]

https://en.m.wikipedia.org/wiki/Telechron

 

[Wes_in_VA]

https://en.m.wikipedia.org/wiki/Telechron

That was pretty interesting

 

[Pio1980]

I had thought Laurens Hammond was credited for putting the US on precise line frequency, but this is pretty conclusive.

 

[Harvestor]

I installed a HZ CPS Meter in my home to monitor both my generator and AC Service
It varies between 59.7 & 60.3 throughout the day .
I believe that it is normal.
And effects nothing.
I'd only start to worry if it varied 3 Cycles Per Second

 

[AdamAnt316]

As a collector of line-synchronous electric clocks (both analog and digital), I have several clocks plugged in at any given time, and keep track of how many seconds they've drifted ahead of or behind the WWV time signal. As of this writing, the synchronous clocks are roughly 26 seconds ahead of WWV, which is the most I've seen them out-of-synch in a long time. Generally, they're within ±10 seconds of WWV; I last synchronized them shortly after Daylight Saving Time ended. Here are some pictures of a few of my line-synchronous clocks:

And here's my primary WWV reference, the Heathkit GC-1000 "Most Accurate Clock":

 

[gadget73]

That "eyeball" clock with the crosshares is pretty cool. What is that?

 

[a_retent]

As a collector of line-synchronous electric clocks (both analog and digital), I have several clocks plugged in at any given time, and keep track of how many seconds they've drifted ahead of or behind the WWV time signal. As of this writing, the synchronous clocks are roughly 26 seconds ahead of WWV, which is the most I've seen them out-of-synch in a long time. Generally, they're within ±10 seconds of WWV; I last synchronized them shortly after Daylight Saving Time ended. Here are some pictures of a few of my line-synchronous clocks:

Would love to have an art deco Telechron like that, nice stuff!

 

[AdamAnt316]

That "eyeball" clock with the crosshares is pretty cool. What is that?

It's an Aurora clock, from the '70s. It uses a series of polarized filters which are supposed to change colors as the hands turn; unfortunately, the filters on mine have been cooked to an amber color by the incandescent bulb behind them, and you can barely perceive any color change. Fortunately, parts are available from a company called ChronoArt, who also sells reproductions of it and another similar clock called the Prisma.

Would love to have an art deco Telechron like that, nice stuff!

Yeah, Telechron made some great clocks back in the day. I've owned several of them, and they're some of my favorites. That 4F51 "Telart" was the first one I found; I scored it in an antiques mall for all of $12. Here are a few more of the Telechrons I've picked up over the years:

(there's more to this one than meets the eye)

(uses a Telechron motor; the case was apparently made by Chelsea)

 

[Pio1980]

I have a Bakelite ballfoot deco somewhere.

 

[nasadowsk]

Anything that derives its timing from the power line, can be affected. Also, large industrial motors can get upset from the changes.

Years ago, frequency stability was a big thing. Now, a lot of the 'renewables' folks want to loosen the standard, because for whatever reason they don't think it should apply to them. Which makes no sense because they're inverter driven and should be able to stay at 60Hz on the button till the cows come home.

IIRC, the German or might have been the Austrian railways bumped their catenary frequency up from exactly 16 2/3rds Hz to 16.7 Hz a while back. There was some weird technical reasoning to it, though I suspect also static inverters can hold 16.7 Hz better than 2/3rds, which is a repeating decimal (computers hate that stuff). It's a small enough change to not affect anything (actually, it's very very slightly better for the transformers.)

FWIW, Amtrak in the US is the last big user of 25Hz power...

 

[Pio1980]

Tonewheel organs like Hammond rely on line frequency for pitch.

 

[AdamAnt316]

Tonewheel organs like Hammond rely on line frequency for pitch.

Indeed they do. Not many people know this, but Laurens Hammond invented a sort of AC synchronous motor which he used to produce clocks, an example of which can be seen in the third photo down in my first post in this thread. The motor used in these clocks was not self-starting (Telechron had a patent on that aspect), so you had to spin a small knob on the back of the clock in order to get it counting seconds; as a consequence, it was possible to get the motor to start spinning backwards, and/or at a different multiple of the intended speed.

In the mid '30s, Hammond's clock motor patent was invalidated due to prior art, so he started looking for new uses for said motor. After a few failed attempts, including a motorized bridge-dealing table, he came up with a motor-driven 'tonewheel' generator which he was able to successfully patent. Of course, the motors used in Hammond's organs still weren't self-starting; early prototypes supposedly used a side-mounted handcrank to start the motor a'la early automobiles, but they soon hit upon the idea of using an additional (non-synchronous) motor to spin the synchronous motor up to speed, hence the run/start switches on most tonewheel-based Hammond organs. Later organ models did adopt a self-starting synchronous motor.
-Adam

 

[a_retent]

...the motors used in Hammond's organs still weren't self-starting; early prototypes supposedly used a side-mounted handcrank to start the motor a'la early automobiles, but they soon hit upon the idea of using an additional (non-synchronous) motor to spin the synchronous motor up to speed, hence the run/start switches on most tonewheel-based Hammond organs. Later organ models did adopt a self-starting synchronous motor.
-Adam

I played a B-3/Leslie combination for a few years way back when, loved the sound of it and still do. I fondly remember having to do the start-up procedure before playing and if you didn't hold the switch in "start" long enough you got to do the process all over again.
Aahhhh the good ol' daze.

Thanks for the link to the "telart" btw.