Do they detect the light flicker or the ambient ac field. Light flicker is
120 Hz.

Very interesting,

John  WA4WDL

From: "tom jones" epoch_time@yahoo.com
Sent: Wednesday, April 20, 2011 9:43 AM
To: time-nuts@febo.com
Subject: [time-nuts] 60hz disciplined watch

My bet would be flicker and divide by 120. Doesn't really matter. But since
these watches use the light to charge the battery, sensing the frequency is
a byproduct. Nice and simple.

On Wed, Apr 20, 2011 at 10:10 AM, jmfranke jmfranke@cox.net wrote:

I wonder if it's smart enough to have a sanity check to determine
whether the line frequency is 50 vs. 60 Hz?

BTW -- I have an Ecodrive watch, but it's radio controlled (as well as
solar charging), so haven't seen any reference to this setting method
before.

John

On 4/20/2011 10:13 AM, paul swed wrote:

Le 20/04/2011 16:17, John Ackermann N8UR a écrit :

I don't buy it. Makes a nice urban myth though. Incandescent sources
don't flicker like fluorescent sources and the Skyhawk user manual does
not recommend charging in front of flouresecent tubes to maintain accuracy.

In message 4DAEEFF1.80906@sfr.fr, cook michael writes:

Not to mention that grid frequency is nowhere near as stable in the
claimed tau as a 32.768kHz xtal...

Now, if they averaged for a month, then maybe...

And before anybody claims they do:  You do realize that mains may
have the same frequency, but not the same phase from one 3-phase
transformer to the next ?

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

I had (still own, dead in a  drawer) one of the 1st gen EcoDrives, and
couldn't keep it charged during the winters here in sunny Seattle - so, I
replaced it with a radio-disciplined Casio, which lasted about 8 years.

When we went to DisneyWorld 2 years ago in August, it developed some
condensation issues; and so I replaced it at Christmas with a NEW Casio
"WaveCeptor" that's radio disciplined and also solar-charged like the
EcoDrive.  So far, so good with this one, it's had no problem staying
charged, even with our latest cold, dark winter.  It DOES occasionally
lose WWVB for a few days at a time; but, when it gets a signal back, it
syncs right up again. I haven't checked it against a REALLY accurate
source; but it does seem to be right on with the WWV voice signals.  I
just purchased a Thunderbolt starter kit from the guy in China; it showed
up earlier this week - hopefully by this weekend I'll have it installed
and then can check watch against that.

Clay
N7QNM

time-nuts-bounces@febo.com wrote on 04/20/2011 10:38:41 AM:

There is plenty of 120 Hz (or 100 Hz) ripple on incandescent light.  No
fluorescent lamps required.  It's easy to test the issue with a photodiode
and a scope.

Joe

Thats what I also thought though did not plan to test it.
As for mains stability. They are indeed stable over time weeks and months
and are corrected. This was a use case for numbers of the austron clocks and
freq references.
Plus the frequency accuracy is needed for inter-tie networks and power
sharing/selling.
Regards

On Wed, Apr 20, 2011 at 11:17 AM, Joseph M Gwinn gwinn@raytheon.com wrote:

In message BANLkTimuxPs8gBxP99ra8iJzvhEotp8ong@mail.gmail.com, paul swed writ
es:

Are you sure ?

Here in europe that was lost in the "privatization" of the grid: Nobody
was charged with paying for the extra power needed to capture lost
cycles, so now they just try to keep it close to 50.0Hz and don't
care about the integral.

I would be surprised if it were any different in USA.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

On 4/20/11 8:26 AM, Poul-Henning Kamp wrote:

It's probably somewhat better, because there are long distance
transmission lines which rely on careful management of relative phases
(and by extension frequencies) to control the power flow on the line.
California consumes about 50 GW (peak)  (26 GW for Ca Independent
System Operator as I type this).  The two Pacific Intertie lines (one AC
and one HVDC) carry 7GW-ish.  That AC line is quite the challenge to
stabilize (it's 1000km long, and I've heard that transients take hours
to die out). (and, of course, they use GPS heavily to provide an
accurate time reference for reporting instantaneous phase and amplitude
of the lines)

I seem to recall a site somewhere that gave statistics (in quasi real
time) of the system frequency here in Southern California.

Hi Poul-Henning,

On Wed, 20 Apr 2011 17:26:15 +0200, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:

...

...

where do you get that information? The ETSOE(transmission operators
network)-handbook
which specifies the control-loops for frequency/phase have a section on
TIME CONTROL.
They define different levels of allowed offsets between integrated network
phase and UTC.

There are three bands with allowed deviations of +/- 20, 30 and 60 seconds
(target, tolerated and exceptional).

https://www.entsoe.eu/resources/publications/entso-e/operation-handbook/

--- QUOTE from Section P1, Page 29 ---
D. Time Control
[UCTE Operation Handbook Appendix 1 Chapter D: Time Control, 2004] {update
under preparation}

Introduction
The objective of  TIME CONTROL is to monitor and limit discrepancies
observed between
SYNCHRONOUS TIME and universal co-ordinated time (UTC) in the  SYNCHRONOUS
AREA.
Reasonably it is applied during periods of uninterrupted interconnected
operation, where the
SYNCHRONOUS TIME is the same in all control areas.
...
A discrepancy between SYNCHRONOUS TIME and  UTC is tolerated within a range
of ±20 seconds (without need for time control  actions).
---/QUOTE---

Greetings from Germany,

     Chris

On 4/20/11 8:53 AM, Jim Lux wrote:

I found this in a generator interconnection agreement:

This frequency response control shall, when enabled at the direction of
CAISO, continuously monitor the system frequency and automatically
reduce the real power output of the Asynchronous Generating Facility
with a droop equal to a one-hundred (100) percent decrease in plant
output for a five (5) percent rise in frequency (five (5) percent droop)
above an intentional dead band of 0.036 Hz

Here's a nice training presentation about how they measure and manage
system frequency and relative phase (to fractions of a degree)
http://www.phasor-rtdms.com/downloads/guides/CAISO_RTDMS-Training01312006.pdf

There's some pictures of actual frequency disturbances during
transients, and I leave it as an exercise for the reader to turn that
into an AVAR spec.

That's all about short run (taus of tens/hundreds seconds)...
The system generally regulates frequency over 100k seconds (a day) to
keep electric clocks reasonably "on time". I think the standard is "no
more than 2 seconds deviation from UTC" which implies, what, something
like 5E-4 ADEV for tau of 100,000 secs?

tvb's data at http://leapsecond.com/pages/mains/  seems to show similar
statistics.  His plot of "phase data" is labeled seconds, and if that's
right, then his local power is substantially worse than the "2 second
error" metric.

In message 4DAF0B0D.4080501@earthlink.net, Jim Lux writes:

Neither that text nor any other I have been able to find, guarantee
that the integral (= long term average) of the frequency will
converge on 60Hz, only that the instantaneous frequency will stay
in an particular range.

That data confirms what I said:  Maybe if you average over a couple
of months, but the practical problems related to doing that are
enormous.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

On 04/20/2011 05:26 PM, Poul-Henning Kamp wrote:

The mainland Europe grid (which you are not on, I know..) looks like this:

http://n1.taur.dk/grid/plt.png
http://n1.taur.dk/grid/pltw.png (very large with grid)

y axis is phase in seconds, x axis is time

The plot is 130 days long, 60sec/130d= 5ppm
but
in that plot is also 5 days in a row where the frequency is 230ppm high.

/Kasper Pedersen

On 4/20/11 9:39 AM, Poul-Henning Kamp wrote:

There's the "integrated time shall not deviate more than 2 seconds from
actual" sort of requirement.  I don't know what the integration interval
on that is, but I think it implies that in any given day, there will be
60*86400 cycles plus minus 120 cycles. And that further, a sequence of
+120, +120, +120 on successive days wouldn't be allowed.

I also noted that they seem to want the "corrections" to be done at the
top of the hour (they speed up or slow down the 60 Hz until they're
realigned)..  I don't know, off hand, how much difference that would
make in power flow (say they adjust by 0.01 Hz... over 1 second, that's
a phase shift of 3.6 degrees, which is pretty big in the power
management world)

On 4/20/11 9:44 AM, Kasper Pedersen wrote:

What's that huge excursion between Christmas and New Years?  Is that a
reflection of a big load or generation change during the week?

On Wed, Apr 20, 2011 at 10:00 AM, Jim Lux jimlux@earthlink.net wrote:

I used to know and older engineer who worked with power systems.  He'd
be in his late 80's now.  He explained the process they used to bring
on-line a new generator.  Connect a light bulb between the "hot" line
of the generator and the utility power and adjust the phase and
frequency until the bulb went out and stayed out, then throw the
switch.  not exactly high tech.  I'd bet there are still places where
this is what's used.

--

Chris Albertson
Redondo Beach, California