Frequency standard

It's still not going to give you any useful indication of when the power is going to fail at *your* place. So what's the point measuring this?, if as I gather your point is to predict blackouts and such? Unpredictable local storms, car crashes, transformer failures, and nearby local load switching are going to potentially cause you more blackouts and/or brownouts.

Dave.

Reply to
David L. Jones
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The pot lines take *HUGE* amounts of energy, in Australia around 15% of total supply. To refine 1 Tonne of Al, requires approx 15MWh of electricity (which is why recycling Al is very cost effective).

For example, the Tomago Aluminium smelter in NSW, uses around 690MW of power, and is supplied directly by Transgrid from its own 330KV substation. The smelters also get heavily subsidised electricity, paying around 1/3 of what other industries would be paying, (and much less than you and I pay).

The pot lines can loose power for 4-5 hours without them solidifying. By dropping and Al smelter load, the power system can quickly recover from a loss of a generator. When replacement generation has ramped up, supply can be restored. Their supply contracts do however require that power be restored within a certain time, before the pot lines are in trouble, and the maximum number of times they can be load shed etc. The pricing and conditions was all very political to encourage (bribe?) the smelter operators to build there smelters in the local area, and provide employment etc.

David

Reply to
David

Now that's putting it into perspective. :-)

My little UPS from Rockby Electronics [free plug] has saved me from losing data quite a few times during brief interruptions caused by storms and car accidents bringing down power lines in the local area.

Bob

Reply to
Bob Parker

Think it was EA that ran a project for a TV derived frequency reference around 15 years ago.

They claimed atomic clock accuracy, since that's what most, if not all, of the commercial channels used to derive their horizontal sync.

I used one as a reference for a frequency counter, with good results, up until our TV went digital (I'm on Optus satellite TV). Presumably it would still work on ground based analogue transmissions (which I don't get).

It was available as a kit IIRC.

--
John H
Reply to
John_H

One crude way to watch what the mains frequency's doing is to be in an area of poor (analog) TV reception where there are high voltage power lines nearby. Wait for a nice humid day when the insulators are crackling, then watch a low VHF channel (Channel 2 is good) and watch what the horizontal lines of RF noise from the insulators arcing are doing in the picture. This is comparing the mains frequency against the very accurate

50Hz field rate timing of the TV station. If the noise lines are moving up the picture, the mains frequency's above 50Hz and vice versa. I think I got that the right way around. :-) You could use a stop watch to measure how long it takes for the interference to do a complete 'loop' and do some calculating of the exact mains frequency.

Bob

Reply to
Bob Parker

Jim Rowe based it on a simple circuit I submitted as a Circuit and Design Idea. ;-)

Reply to
Bob Parker

!5 years ago? TV stations tend to use a frame store at the transmitter to clean up switching glitches, and they regenerate the color sync with a cheap crystal, typically four times the color burst. These are accurate to about 10 hz. Prior to that, live network feeds were run from Rubidium frequency standards.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
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Reply to
Michael A. Terrell

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.

Reply to
David L. Jones

Thanks for the info, Michael. Back then, Jim Rowe got the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) to do some precise measurements of his TV-derived frequency standard. They found that all the networks were very accurate, but a couple were super-precise. Maybe it's all different now and GPS is the way to go?

Bob

Reply to
Bob Parker

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

Bob

Reply to
Bob Parker

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.

Reply to
David L. Jones

GPS is the way to go now for sure. Even Rubidium references come up cheaply on eBay these days.

Dave.

Reply to
David L. Jones

Strange considering Telstra maintained the Australian frequency standards at the time, not the CSIRO. Telstra has now given it away, but last I heard the CSIRO was not interested. Didn't want to spend the money (the same reason Telstra gave it away)

go?

Well the ABC-2 clock was running 1 hour and five minutes fast, (compared to AEDT and their programs) most of Sunday morning. I wouldn't have too much faith in them any more :-(

MrT.

Reply to
Mr.T

It may have taken longer for the frame store equipment to migrate from type 'M' NTSC in the US to other countries. Want to have some fun? Try synching two different brands of frame store to the transmitter site's sync generator for live programming from two other cities. A one degree phase shift was visible on air.

GPS derived 10 MHz lab standards are common these days. There was a construction article on a website to convert a surplus rack mount cell phone base station GPS receiver into a low cost lab standard.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
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Reply to
Michael A. Terrell

Saw something like that at:

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petrus bitbyter

Reply to
petrus bitbyter

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