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Thread ID: 71115	2006-07-27 01:18:00	Hot water cyclinder:How does it work and how much power....	lance4k (4644)	PC World Chat

Post ID	Timestamp	Content	User
473897	2006-07-29 15:58:00	I was much younger and infinately more impressionable when I heard about the induced power via the coils of wire under the transmission lines . . . . so it might've been like the lady, the wet poodle and the microwave story . . . . . somewhat plausable, totally junk . Damn . . . now you've busted the memory I had of the one and only time my father told me anything in confidence . . . . :xmouth: .	SurferJoe46 (51)
473898	2006-07-30 03:09:00	I don't think I'd bother with a "coil" of wire . You want an aerial which will collect radiated power in the near field . It's volt/metre which counts; a bigger (longer) aerial will pick up more energy . I would use a long wire parallel with the power line . Earth one end, and you'll certainly see some volts at the other end . But there'll never be any great current . I don't think Billy's idea that the power loss would be detectable by impedance discontinuities would worry me . With a wavelength of 5-6000 km , and sometimes hundreds of kV on the lines, TDR test equipment isn't often used . (My rough guess at the characteristic impedance of the big lines is about 600-800 ohms, BTW, what is the diameter of those conductors -- I guessed 3"?) . The impedance detection used on these lines detects arcover, (shorts) by comparing the current and voltage in each section . It's so that the protection switches can be operated . The amount of power you could couple out wouldn't even be noticed . The whole idea of the power distribution system is that current will flow to loads . But the inspection crew in their helicopter might notice something . RF can do funny things . Wireless World occasionally had a story about fires near naval bases in England . The big transmitters had enough output to produce sparks from metal objects . When the objects were gas stoves . . . I think the best way to get power from a 200 kHz transmitter would be with stakes driven into the ground . The earth (image) current would give quite a good voltage gradient for quite a distance past the earth mat . I've measured 2v pk-pk (common mode) on long open wire transmission lines a few miles from Gebbies Pass . 3YA has (had?) 150 kW, I think, but that was out of the near field . I've had 50 V pk-pk on 75 ohm receiver inputs with horizontally polarized arrays, a few hundred metres from a 100 kW pulse transmitter .	Graham L (2)
473899	2006-07-30 06:31:00	The capture of some "useable power" from induction under transmission lines is real . But not practical . Not sure if it's still in use (photovoltaic may have rendered it obsolete) but north of Hanmer Springs there was a remote radio repeater (belonging to the old NZED) that was powered by a lengthy aerial conductor under the ISL-KIK (Islington to Kikawa) 220 kV line . As they also owned the line it was legal . But the problem was regulation of the small induced power level, as it was totally dependent on the ISL-KIK circuit load current . You would only get a few watts, getting close enough to get anything useful is a tad difficult at 220kV . Really only useful for a battery charger or similar . But there would be no way to detect it, as it would simply show up as inductive losses . They would be incalculable as a proportion and I doubt that the "differential protection" circuits would even know they were there .	godfather (25)
473900	2006-07-30 11:08:00	I don't think I'd bother with a "coil" of wire. You want an aerial which will collect radiated power in the near field. It's volt/metre which counts; a bigger (longer) aerial will pick up more energy. I agree with the antenna theory for voltage capture, but that is of no practical value for gathering usable energy levels at 50Hz. You need close inductive coupling for that, in order to transfer enough energy to produce actual power. I do think that any system capable of drawing usable power would be potentially detectable via line tests, I have seen some amazing technology in recent years that can locate impedance variations over long distances, and they would not be doing their search at low frequency. It possibly might not work on power lines, but I see no insurmountable technical barriers. I've measured 2v pk-pk (common mode) on long open wire transmission lines a few miles from Gebbies Pass. 3YA has (had?) 150 kW, I think, but that was out of the near field. I've had 50 V pk-pk on 75 ohm receiver inputs with horizontally polarized arrays, a few hundred metres from a 100 kW pulse transmitter. Hmmm....That's about 30 watts of RF energy, or nearly 700mA in the receiver input. I'd expect smoke at those levels unless the pulses were of very short duration, in which case the mean energy level would be pretty much useless. I still don't think that any useful power is likely to be realised. Bear in mind I'm not saying that it is impossible to couple energy from a high tension powerline, I am simply saying that the amount of energy obtained is not worth the effort. Under the right conditions you can get free fluorescent lighting though, that is quite easy to achieve from both powerlines and high power RF sources. I used to use a 4 ft fluorescent to check for power radiation from 25 watt marine transmitters running on a base loaded whip in my workshop. Cheers Billy 8-{)	Billy T (70)
473901	2006-07-31 05:04:00	I read somewhere (in Scientific American?) about a method of getting power from the extrahigh voltage distribution lines . Electrostatic motors . :D Billy, I wish you would read what I write . :( I mentioned "voltage", not current or "usable power" . A coil as described would be useless for anything, hardly even for detection, as was said . . I didn't suggest running a water cylinder from the long wire . As far as I know, the only impedance test on the grid is the continuous monitoring for protection, and that's just looking for high current/low voltage . The amount of corona on a long line would exceed the amount of energy pulled by anyone with a long parallel line . Wet weather would make a big difference . , too . It was a pulse transmitter, as I said; 20 microsecond pulses, at quite low PRF . Not useful energy, but it was enough to take out the front ends , until I put some diodes across them . Curiously FET inputs could take it; it was the transistors in an IC which were fragile . Running a fluorescent tube from a 25W transmitter isn't "free" energy . You'd find it cheaper to plug it into the 3 pin socket . Some of the NZ stories on this theme mention dairy sheds lit by the captured energy . I suppose electric fences is the obvious application . :D	Graham L (2)
473902	2006-07-31 06:34:00	Billy, I wish you would read what I write. :( Yeah, I did read what you wrote Graham, but the point at issue was "usable power levels" not merely detectable voltages, so while I liked your technical experiences, they didn't add a whole lot to the discussion, hence my comments on relevance. Running a fluorescent tube from a 25W transmitter isn't "free" energy. You'd find it cheaper to plug it into the 3 pin socket. Gee, I wish you would read what I write Graham. :p I didn't use the fluorescent for illumination, and I don't recall claiming it to be free energy either, I used it to verify that radiated power existed. We lacked a suitable 25W dummy load or power meter you see, so a short press of the mic key lit up the fluorescent and gave a quick indication of RF out. Cheers Billy 8-{) :D	Billy T (70)
473903	2006-07-31 07:01:00	OK, all that notwithstanding, here are some real figures :) I dug out an old frame aerial that I used to use for medium wave DXing before all the available 'broadcast' wavelengths were sold off for Maori radio and other junk local radio etc. Octagonal shape, 650mm nominal 'diameter', Q~200. At 26Km from the Titahi Bay 567Khz medium wave transmitter, with the aerial tuned to resonance, I can get 175mv into a 10Mohm, 22pf probe connected to an HP 400E voltmeter. It is left as an exercise for anyone to work out what sort of power could be obtained within say 500 metres of the masts. :)	Terry Porritt (14)
473904	2006-08-01 03:19:00	. . . Under the right conditions you can get free fluorescent lighting though, that is quite easy to achieve from both powerlines and high power RF sources . "free fluorescent lighting" does not mean free or illumination? But you didn't give us the benefit of your experiences getting it from the powerlines . I believe they frown on bypassing the meter . :D In case you have never noticed, this section of the forum is not always relevant to anything Billy . [quote=Billy T] . . . I do think that any system capable of drawing usable power would be potentially detectable via line tests, I have seen some amazing technology in recent years that can locate impedance variations over long distances, and they would not be doing their search at low frequency . It possibly might not work on power lines, but I see no insurmountable technical barriers . [/b] Any system capable of drawing usable power is usually detectable by a visual inspection . The distribution system isn't ever going to be shut down to look for such things . I can assure you that impedance measurements on the high voltage distribution lines would be fairly meaningless . They are so long that there would be rain at some part, and the capacitance (and thus impedance) change that causes is quite severe . That would also seriously affect any TDR measurements . (That's quite apart from the fact that you wouldn't get me doing those measurements on lines at a few hundred kV . ) Anyway, the power system doesn't use the maximum power theorem, and matched lines, so I have strong doubts that the impedance is ever measured, except by the ratio of volts and amps, which is a "system" rather than "line" thing, because it depends on the load . A flashover fault will cause a sudden change in it, which will normally cause urgent switching operations to isolate the fault, rather than searches for freeloaders . The source impedance of the generation end is as close to zero as they can get it . The real part of the transmission system impedance is as low as they can economically get it, and there is a fair amount of money spent on capacitors and inductances to correct the imaginary part . Terry, you wouldn't get within 500 metres of the tower . That's why they have the big fences . I remember being told years ago that you have to walk with care near the base of the tower . The voltage gradient across the ground can cause quite interesting effects if you take long paces . Two stakes in the ground and a big diode would give you some useful power . :D	Graham L (2)
473905	2006-08-01 03:42:00	P.S. Terry: Again, I think a long wire would be better for extracting energy at 567 kHz than a loop. Field strength is measured in volts/metre, so if you want more volts, you need more metres. A tuned circuit can only use what it's got; if the tuning improves the volts, you are raising the impedance which is supplying those increased volts (or millivolts). You used that frame's directionality to improve your signal to noise+signal ratio, when more signal+noise can actually be a handicap.	Graham L (2)
473906	2006-08-01 05:12:00	"free fluorescent lighting" does not mean free or illumination? But you didn't give us the benefit of your experiences getting it from the powerlines . I believe they frown on bypassing the meter . :D Sorry Graham, I should have explained . Firstly, in that context "free" simply meant it wasn't a source that you should really be paying for . Secondly, the light output was not adequate for what one might usually call "lighting-grade illumination" but it was bright enough to show the presence of RF under daylight conditions As for getting free lighting from powerlines, the voltage field below a 110kV or 220kV line is often sufficient to strike a flourescent tube and produce a reasonable amount of light output . Holding one end of the tube in your hand and waving it about will usually provide a pretty fair Star Wars light-sabre imitation at night . For more light, put a short metallic extension 20-30cm onto the free end (connecting to the filament pins), and wire the end you hold so that you make an electrical connection between your hand and those filament pins as well . Bare feet completes the "illumination enhancement" program . It is quite harmless and reasonably painless unless you are particularly sensitive to very weak electric shocks . I can think of several ways to get similar (weak) illumination inside a building situated below the lines . The voltage field below HV lines ranges from 2 kV/m up to 5 kV/m, and may be significantly higher if you are on rising ground under the mid-point of the lines between pylons (maximum droop) and getting within 3-4 metres of the minimum safe distance . You need about 2 . 5kV/m to get the tube to illuminate, though some may work at lower voltages . Cheers Billy 8-{)	Billy T (70)
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