# Frequency standard - Page 2

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Re: Frequency standard

Neat!

No HV lines within cooee of my place though, nor above ground power
lines for that matter.
Come to think of it, I don't have an analog TV any more, nor an analog
band antenna!

Dave.

Re: Frequency standard

Darn! Now you won't know when the next blackout due to the network
being overloaded is going to happen. :-)

Bob

Re: Frequency standard

Guess I'll have to work on a running average or something, I think
it's currently about once every year. Pretty darn good IMO.

Or perhaps I could make a divining rod out of some cryogenically
frozen oxygen free copper cable or something? :->

Dave.

Re: Frequency standard

Crystals has an inverse parabolic frequency variation with temperature.
If you know or can measure the parameters of that parabola, you can
measure the temperature and compensate the timings down to the order
of a couple of seconds per month.

That might be useful for a 0.000001Hz standard, though not as a 50Hz
frequency standard. Depending on exactly what you want, you might be
able to get away with counting 50Hz cycles over a longer (accurate)
time, to determine variance from the nominal frequency.

Clifford Heath.

Re: Frequency standard

What is your real application here?
If it's just to get an occasional spot frequency check then your
crystal should do just fine.
But the easiest way to do that is to simply use a frequency counter
that has reciprocal measurement (to get a lot of resolution at low
frequencies like 50Hz).

If you are talking long term drift accuracy and/or logging then that
is a different ball game.

Dave.

Re: Frequency standard

Hi Suzy,

We have used these temperature compensated oscillators from Hy-Q.
Significantly better than a normal crystal.

http://www.hy-q.com.au/pdf/10120029.pdf

David

Re: Frequency standard

"Alan Peake"

** Huh ???

That is way more than it actually varies.

You method must have been  flawed.

......    Phil

Re: Frequency standard

Agreed Phil. And for all those interested, see this site for the UK grid.

http://www.dynamicdemand.co.uk/grid.htm#

Re: Frequency standard

"Suzy"
"Phil Allison"

** That web sites created by complete amateurs  -  greenie loopy ones too.

The supply frequency is not so simply related to demand as they naively
claim.

IOW  -  it's bollocks.

.......   Phil

Re: Frequency standard

But isn't it true, Phil, that more demand than supply will drag down
alternator shaft speed and thus frequency, and vice-versa?  Apart from the
clock "make-up" events in times of slow load, what other factors would you
offer that influence mains frequency?

Re: Frequency standard

I meant "low" of course. BTW, that site looks quite good to me, and the
meter is natty.

Re: Frequency standard

Balancing a load is always difficult, like driving a car at exactly the
speed limit, you will vary somewhere around the desired setpoint.
Generators use PID controllers to maintain correct load but there will
still be variations due to time lag of the system and over-correction by
the controller. On a big grid these variations will be smaller.

Slightly off topic but interesting, the grid load on a typical week day
has a sharp peak at exactly 6PM.

Elmo

Re: Frequency standard

Yes, that's what I meant. BTW, how do you know when the sharp peak is (if
not by looking at a drop in frequency)?

Re: Frequency standard

I work at a power station, and on our internal internet system we have a
load graph. We can bring up load data going back several years. It's
only updated every ten minutes. I haven't looked at the frequency
recordings for ages but I'll have a look when I go back to work.

The load generally rises during the day, drops off a bit about 5 pm and
then peaks at 6pm as everyone switches the tv on to watch the news over
a cup of tea. On a hot day the the load doesn't drop off but keeps
rising about 5 pm. I blame this on daylight saving, people leave a cool
air conditioned workplace and come home to a hot house and put their air
conditioners on flat out to cool the house down. If daylight saving was
an hour opposite you wouldn't be coming home at the hottest time of the
day. It's a way of passing cooling costs onto the worker.

Elmo

Re: Frequency standard

Any info on how NSW is going for summer capacity?

My 2c is that I escaped a number of outages this summer as the heat
didn't happen. So I am wondering if we are going to cop them next summer
(if the heat comes back)?

Re: Frequency standard

"Suzy" = not@valid

**  ROTFL   !!!

Better go learn about ohms law  -   honey ...

......   Phil

Re: Frequency standard

Great! I'll take much more notice of your replies than that strange strange
person PA!

Re: Frequency standard

"Suzy"
"Phil Allison"

** I will not answer dumb questions or engage in pointless chat.

The folk behind that site have NO credibility and have given NO proof of
their claims.

The idea put forward that individual appliances ought to dance to the tune
of tiny variations in the AC  frequency is

UTTERLY    LUNATIC !!!

A typical fuckwit greenie idea.

Like banning incandescent bulbs and transformer plug packs.

.......  Phil

Re: Frequency standard

I agree with Phil on this one, the idea is lunacy.
The web interfaced frequency meter is neat though, although it's not
even calibrated:

"We have not yet callibrated the meter, so the number you can see may
differ slightly from the real grid frequency by a constant small
amount.
The reason why we show so many decimal places in the frequency is to
ensure you can see it change. The changes (the movements of the
needle) should be quite accurate.
There will be a slight delay in the signal because it takes at least
two seconds to send the data over the internet.
Disclaimer: Please don't rely on our grid meter for any industrial or
other applications. We can't guarantee accuracy or reliability!"

Dave.

Re: Frequency standard

For Suzys purposes it doesn't have to be calibrated, she's more
concerned with fluctuations and differentials than the actual frequency.

Elmo