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Non Life Sciences => Technology => Topic started by: syhprum on 26/02/2013 20:18:41

Title: Can I harvest energy from overhead wires?
Post by: syhprum on 26/02/2013 20:18:41
I wish to harvest energy from nearby 400Kv power lines so to this end I suspend a 100 meter long wire 1 meter above the ground below the power line that is 10 meters above the ground with a ground wire beneath it.
I now have a capacitive potential divider formed by the capacitance of my wire to the power line and its capacitance to the ground wire.
To know how much power I can draw I must know the reactance of these two element's of the potential divider which will tell me the open circuit voltage induced in my wire and its internal impedance as a power source.
I would of course have to use a transformer to convert the high voltage induced in my wire to a lower value for my load.
When I check the tables for capacitance per unit length I find that a voltage of 300Kv is induced in my wire that has a capacitance of .004183 micro Farads hence an impedance of .761 meg ohms at 50Hz If my load terminates this until the voltage is halved it seems that I can harvest 29.57 Kilowatts would someone care to redo the calculations !!
Title: Re: Havesting power
Post by: CliffordK on 26/02/2013 23:05:35
I've tried that...

I have a main trunk line running across my property.
Strung an electric fence wire under it (single stranded?)

I couldn't really seem to get any measurable volts/amps in my wire.

Perhaps I should try it again with a rectifier and capacitor.

 [ Invalid Attachment ]

Do I need some other kind of a "ground"?  I could add two capacitors, with a lead going into the ground between them (perhaps rectified too).

Of course, keep in mind that power, at least in the USA is distributed in 3 phase, with the sum of the three phases equaling ZERO.  I can offset my collection wires to one side or the other, to get more from one of the wires, but the distance between the distribution wires is less than the distance from the wires to the ground.
Title: Re: Havesting power
Post by: RD on 27/02/2013 04:48:50
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.thenakedscientists.com%2Fforum%2Findex.php%3Faction%3Ddlattach%3Btopic%3D27039.0%3Battach%3D10663%3Bimage&hash=bf6fb9c8e47331e1cd7c88877a2da98e)
http://www.thenakedscientists.com/forum/index.php?topic=27039.msg286115#msg286115

To the naked eye the fluorescent tubes are much dimmer (http://www.richardbox.com/field%2005.htm), each scavenging maybe a couple of Watts when directly below the 400kV power lines. 

A hula-hoop wrapped with many turns of wire, positioned vertically below the distant power lines may be worth a try.

However this could be hazardous and  illegal : if the hula-hoop inductor had many turns of wire the voltage could become high enough to deliver an electric shock, (like a step-up transformer (https://en.wikipedia.org/wiki/Transformer#Induction_coils)). Theoretically this energy harvesting could be either be a form of theft or nominally interfering with power supply,
the charge (no pun intended) could be the same as people who fiddle their electricity meter, even though you're only stealing scavenging less than one Watt of power.

Quote
Energy Scavenging for Monitoring of Overhead Power Line Networks

 [ You are not allowed to view attachments ]

( the electric field directly below pylons, 1m from ground, could be around 1kV per meter )
www.ama-science.org/home/getFile/ZwZm

Quote
Energy Harvesting from Electromagnetic Energy Radiating from AC power lines.

 [ You are not allowed to view attachments ]
http://users.ece.cmu.edu/~vikramg/docs/hotemnets11.pdf
Title: Re: Havesting power
Post by: syhprum on 27/02/2013 07:37:50
I think I have over done the capacitive coupling between the overhead line and my wire perhaps I would be better to think in terms of volts per meter in which case the voltage induced on my line would be 40Kv and the available power more like 2 KW.
there are several factors that will reduce the available power the overhead line is not a single one but one of a symmetrical group of 6 in a three phase/bi phase system and the power drawn from a capacitive source must include a phase angle consideration.
I am surprised by the null result of ClifffordK,s  experiment but assume the power line is much less than 400KV.   
The use of diodes is a good idea in a relatively low voltage scenario but we must remember we are drawing power from a very high voltage high impedance source and cheap diodes are normally only good for 1KV
PS I have heard it reported that standing under the 25KV lines on the railway station the induced voltage can be sufficiently high for you to feel a tingle from your grounded umbrella.
Title: Re: Havesting power
Post by: CliffordK on 27/02/2013 09:48:20
Looking at the BPA map, it looks like I may only have a 115KV line, although the towers appear similar to the higher voltage lines.

Here are some tower drawings.
http://www.minnelectrans.com/transmission-system.html

That would put your height estimate somewhat low.  They would be 30 to 50 meters high.

I certainly am not able to self-power my electric fence.  While one may need AC to induce a current in another wire or coil, some diodes and a large capacitor would help one capture and store excess power.

I don't think I tried the diodes as above.
Title: Re: Havesting power
Post by: syhprum on 27/02/2013 10:24:12
Experiment to supplement theory always helps so that when the weather improves I will set up a 240v power line 3m high with a 10m harvesting line 0.3m high below it, I estimate that 24V will be induced in the harvesting line that will have a capacitance of 50pF hence an impedance of 63.6 M ohms at 50 Hz.
With diodes and a capacitor to store the energy I should get an output of 33V open circuit and be able to draw 2.26 micro Watts of power.
Results to follow in the spring.
Title: Re: Havesting power
Post by: syhprum on 27/02/2013 12:13:27
CliffordK

As you quite rightly say the sum of the three phases relative to the ground is zero on the high voltage side but to my surprise when I installed a scanner in the USA this does not apply to the low voltage domestic supply as the transformers output a centre tapped 220V supply so that you get two 110V phases and one about 190V relative to the ground.
Title: Re: Havesting power
Post by: CliffordK on 27/02/2013 17:47:47
I would start the experiment with just plain electrical wire, 2 or 3 strands, necessarily keeping the strands close together.

Just BE CAREFUL

Merely plugging in your wire (applying voltage) is likely not enough, but you would also have to have current flow.

In fact, an induction ammeter measures amps, and not volts, i.e., it is dependent on current flow. 

Also, keep in mind that the induction ammeter only works when it is put around a single conductor, not both conductors.

-----------

Thinking about this more.
If your goal is to make an air capacitor.
Then you may not need the current flow, just power, I think.
Title: Re: Havesting power
Post by: syhprum on 27/02/2013 19:22:48
Yes I do not need any current we are only dealing with electrostatic fields here at these low frequencies electrostatic and magnetic fields can be dealt with separately. 
The links posted by RD lead one to some research done by a German company for powering telemetry units actually mounted on the power lines they have the advantage of nearby lines of a different phase for the capacitive voltage divider and seem to aim for a power of about 1 Watt.
If I am feeling really brave I may use a microwave oven transformer to boost the voltage of my experimental power line to about 2 KV but of course I will take great CARE.
 
Title: Re: Havesting power
Post by: RD on 27/02/2013 21:56:33
Fluorescent tubes do require a few hundred volts to start ... http://hypertextbook.com/facts/2003/KarryLai.shtml

So the field strength must be at least a few hundred volts over the length of the tube for it to glow.
Directly under the 400kV pylon there's maybe 1Watt per square meter to be had, you're not gonna be able to run anything powerful like a microwave, but maybe a dozen LEDs via a 1m hula-hoop, ( analogous to those solar-powered garden (http://www.maplin.co.uk/batteries-and-power/solar-and-wind/solar-garden-lights) lamps but powered by "free" electricity rather than the sun).

I'd use a step-down transformer to drop the voltage from the hoop inductor down to a level that cheap electronics can cope with, (otherwise applying hundreds of volts across a cheap diode will destroy it).

[ Given the price of copper wire , increasingly this concept is looking like a false economy : batteries would be cheaper ]
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 28/02/2013 06:27:58
I have been concerned with harvesting energy from the electrostatic field which is of course available at a high voltage but from a very high impedance source which would be difficult to utilise.
There is an alternative source from magnetic field when there is current flowing in the overhead line which can be collected by a loop and will be of a very low voltage but from a very low impedance source that may well be more convenient to use.
You posted a link to a feasibility study using this source that I am yet to study !
When I study this article I find they made a serious error in their experimental setup, for an inductor they are using a transformer with "E" and "I" cores the design of such transformers is intended to reduce the stray magnetic field exactly the opposite to what you need to harvest power from stray fields!!
Title: Re: Can I harvest energy from overhead wires?
Post by: evan_au on 28/02/2013 08:49:00
There are an increasing number of high-voltage DC transmission lines.
50pF capacitance @ 0Hz => 0 power
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 28/02/2013 14:55:54
You have to use a long pole with lots of resistors in series like we used to use for checking the voltage on CRT,s in the bad old days.
Title: Re: Can I harvest energy from overhead wires?
Post by: graham.d on 28/02/2013 17:52:52
Clifford, I think the setup you tried could not work. It is not clear whether you are trying to gather power by the inductive coupling of parallel wires or by capacitive coupling. If the former you should try grounding the left hand end of the collecting wire, then have (say) a full wave rectifier connected to a grounded capacitor. The ground is a "return path". If trying to utilise capacitive coupling it would be best to get the collecting wire as high (close) to the power lines as you safely can then connect a full wave rectifier between the wire and a capacitor with a vertical wire to ground. In either case the power available is limited by the fact that the lines will be placed as a transmission line and the losses to ground minimised by the height and spacing. I would have thought you should get some power out of it though.
Title: Re: Can I harvest energy from overhead wires?
Post by: graham.d on 28/02/2013 17:55:19
Oh yes, use very high voltage components. You may not get a lot of current but you will get a lot of volts.
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 28/02/2013 20:46:43
Long rows of glowing fluorescent lamps may well give the impression that there is plentiful power running to waste that could well could be harvested but when you do the arithmetic things are not so rosy.
Main problem is the very high internal source resistance of any power that is harvested 100M of wire strung up to collect power may yield 5 watts 5KV at 1 milliamp not a very useful PSU the only uses I think of it are to power an electric fence via a spark gap as CliffordK has suggested or to flash xenon tubes every few seconds.
Magnetic field collection fares no better as it requires large iron cored collectors and the current in the lines is well balanced to reduce any stray field.
CliffordK,s scheme would certainly work, the best source of diodes would be from a TV EHT tripler that was commonly used on TV's in the early days of colour.
The power limitation arises from the capacitive impedance of the source 100 M of wire has a capacity of about 500pF and an impedance of about 6 Meg ohms at 50 hZ.
You cannot use a bridge rectifier as you need one end of the output to be grounded if you used a bridge the output would float at half the input potential making it even less useful.
I made a mock up feeding a rectifier from the 240 V main via a 500pF capacitor and found the optimum load resistance to be about twice the value of the capacitor impedance and the open circuit voltage of about 550 V.
I am going to use solar power instead !!!.       
Title: Re: Can I harvest energy from overhead wires?
Post by: graham.d on 01/03/2013 08:33:56
I was thinking that something like 5 watts was all that was being looked for! It's free after all although it would not surprise me if there was some law about "stealing" power from the electricity company.

I don't see how a pair of diodes connected to a capacitor (as shown) can charge the capacitor. When one side goes positive to try to forward bias the top of the cap, it reverse biasses the other diode and floats the bottom of the cap. The capacicitor will not charge but both sdes will just follow the AC signal on the collecting wire. Have I missed something (this is entirely possible) or is there something not shown on the diagram?

With a bridge rectifier I was thinking that you have the collecting wire on one side and ground on the other. The voltages on the two outputs from the rectifier should then be across a capacitor wish should end up at a negative voltage (wrt ground) on one side and a positive voltage (wrt ground) on the other side.

The collector wire position would have to be offset with respect to the power lines (I think someone said this already) as the symmetry of the power lines could result in a null point directly beneath them.
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 01/03/2013 18:25:56
Graham
provided a ground connection is made the output circuit with two diodes and a capacitor becomes a normal voltage doubler if you are not familiar with them I append an explanation below.
It is not possible or should a say useful to use as a bridge rectifier as you want one side of the output at ground potential which you can only do if the input is floating or bi phase

Assume the source has a RMS value of 100 volts then the peak to peak value will be 282 volts when the input goes negative to -141 volts the capacitor C1 is charged to this value via D1 then as it cycles to its positive value it carries this charged capacitor with it and deposits 141 +141 volts into C2 via the upper diode D2 giving an output voltage equal to the peek to peek value of the input.

I have appended a modified drawing that shows the input to Graham,s circuit more clearly
Title: Re: Can I harvest energy from overhead wires?
Post by: graham.d on 02/03/2013 10:17:08
Hi Syphrum. Yes, I understand. The original drawing failed to show the ground connection so I did not persist with it. Of course adding the ground makes voltage doubler. The bridge rectifier also works but, as you say, is unnecessary. I should have given it a bit more thought prior to jumping in.
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 02/03/2013 11:48:15
Graham.d

There is a serious problem trying to use a bridge rectifier neither output terminal of the bridge would be at ground potential as it would have the incoming AC superimposed upon it, you can get away with a bridge when one terminal of the input it at ground potential such as in computer PSU if the rectified output feeds a chopper and is isolated by a transformer and or optocoupler but a bridge cannot feed a grounded load from a grounded source.
A voltage doubler may seem inappropriate as the source impedance is already high but it is the only thing that works.
looking at the input with three different phases feeding thru three different capacitance's it looks like a good excuse for some esoteric maths to make it look scientific !
Title: Re: Can I harvest energy from overhead wires?
Post by: graham.d on 02/03/2013 13:21:56
I guess there would not be a problem with ending up with a DC voltage across a capacitor where one side is X volts more negative wrt ground and the other X volts more positive wrt ground as such, unless as you say, you are trying just to supply a DC supply wrt to Ground. I don't know much about electric fences but when I remember getting shocks from these things when trespassing on farmland as a lad it felt like AC (or at least pulsed).

To end up with something that may be more flexible, how about connecting to collector capacitor to a transformer primary with the other primary input at ground? The secondary would then be isolated and could be managed like any other AC power source.
Title: Re: Can I harvest energy from overhead wires?
Post by: evan_au on 02/03/2013 18:31:39
Talking to someone in the power industry, high-voltage transmission lines typically run around 400 Amps during peak hour, which will produce a magnetic field extending beyond the wires themselves (to infinity, in theory).

As noted in a previous post, the balanced currents in the 3-phase wires sum to zero, so the magnetic field drops off much faster than the field around a single conductor. A receiver coil would need to be carefully positioned relative to the geometry of the wires for best collection efficiency.

The ideal position for a coil to collect power from the transmission line would be directly around each individual conductor (like a current transformer) - but I am sure that would be illegal, as well as extremely dangerous: The transmission line operates at high voltage, and current transformers generate dangerously high voltages if they are left open-circuit for even an instant.
Title: Re: Can I harvest energy from overhead wires?
Post by: evan_au on 02/03/2013 18:37:51
A capacitive pickup suffers from extremely high source voltage, but extremely high source impedance.
An inductive pickup has the opposite problem: very low source voltage and very low source impedance. Even a single silicon diode would block the power output from a small coil.

A resonant circuit helps overcome some of these problems - with a source capacitance of 500pF, you would need an inductor of around 6000H to resonate at mains frequency (ideally with low resistance). But the resonant circuit can still produce dangerous voltages.
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 02/03/2013 19:58:02
The situation with a bridge rectifier is worse than what you suggest (open up a switched mode PSU with a bridge rectifier input and check what appears on the terminals of the storage capacitors with a meter or oscilloscope you will find half the input AC voltage on both terminal's of the capacitors).
you can only use a bridge if you have either a floating or bi-Phase input.
An input transformer or resonant inductor would certainly help but would be difficult to source!
If you don't mind your PSU being mounted on the actual power line which is OK for powering radio telemetry equipment commercial units are available using a capacitive pick a bridge rectifier and a chopper as we are not interested in ground connection for this application.

PS talk of using a resonant circuit made me wonder if a quartz crystal could be used the lowest frequency one I have encountered was 4.8 kHz so a 50 or 60 Hertz one might be possible.
PPS A resonant circuit fed from a magnetic pick up might be the way to go with the more practical values of approximately 1 Micro Farad and 10 Henries
A 1 meter diameter coil with 2000 turns would have an inductance of about 10 Henries. 
Title: Re: Can I harvest energy from overhead wires?
Post by: CliffordK on 04/03/2013 14:40:26
Clifford, I think the setup you tried could not work. It is not clear whether you are trying to gather power by the inductive coupling of parallel wires or by capacitive coupling. If the former you should try grounding the left hand end of the collecting wire, then have (say) a full wave rectifier connected to a grounded capacitor. The ground is a "return path". If trying to utilise capacitive coupling it would be best to get the collecting wire as high (close) to the power lines as you safely can then connect a full wave rectifier between the wire and a capacitor with a vertical wire to ground. In either case the power available is limited by the fact that the lines will be placed as a transmission line and the losses to ground minimised by the height and spacing. I would have thought you should get some power out of it though.

I doubt the power company will like me if I climb their tower, and hang my collector a few feet below their transmission lines.

I already have my electric fence wires under their tower so they can't say much about that, and if they do, I could just remove the wires.  "Agriculture" is legal below the power transmission lines.

Earlier when I was testing, I just used my multifunction tester, with no additional circuitry.  I don't remember if I tried AC or DC, or both.  I was getting some small "ghosts" of values, but couldn't be sure it wasn't static from my fingers or something.

I thought about my circuit some more over the last few days and came up with some "updates", in particular feeding the ground into the rectifier.

 [ Invalid Attachment ]

My biggest problem is thinking where one would connect both the + and -.

Perhaps adding a ground into the linear collection circuit (capacitive)

An alternative might be to just make a coil collector (magnetic).

Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 04/03/2013 16:31:27
I have written this many times but I do not know if has been appreciated if you use a bridge rectifier with a grounded source you get half the input AC superimposed on both the positive and negative terminals unless you are going to feed a chopper and then isolate it with a transformer this renders it pretty useless where as if you use a voltage doubler circuit you can use the DC output directly with a grounded load. 
Title: Re: Can I harvest energy from overhead wires?
Post by: Banjo27 on 26/10/2016 19:57:04
Is there any progress on this ??
I have a transmission line tower on my land and would love to power things using the EMF
Spend enough time under them and touching another person you will make a spark , my vehicle has a faint vibration to it when touching the body from the outside when I'm near the lines aswell
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 26/10/2016 22:40:26
An antenna strung along below a high voltage power line will harvest a small amount of energy but because the low frequency the source impedance will be very high and the amount of energy that can be harvested (stolen?) is very low.
You could feed the antenna into the junction of a pair of high voltage rated diodes with a capacitor between the two ends and one end grounded and it would gradually charge up but I repeat the voltage would be high and the source impedance very high not a very useful source of power!   
Title: Re: Can I harvest energy from overhead wires?
Post by: alancalverd on 26/10/2016 23:25:39
"Stolen" is indeed the correct word. Whilst you might get away with the occasional demonstration of fluorescent tubes and the like, if you harvest more than a few watts on a regular basis and somebody grasses on you, you will be liable for "Theft of Electricity" - the fine might be nominal if the quantity was small but you will end up with a criminal record that can do disproportionate damage to your career.
Title: Re: Harvesting power
Post by: Dezeinstein on 24/11/2016 12:57:32
I think you guys are going about this all wrong. The energy isn't in an inductor, so why would an inductor induce this? the field is in the incorrect direction, so to get anything out, you may only have to use capacitive plates and an avramenko plug across the plates to output some energy. The smaller the diodes, the better your safety factor. This way if the voltage is too high , the diodes will explode. try this, put a copper plate on the top, glass in the middle and aluminum plate on the bottom. use the don smith experiment but in reverse. Take the plates, cut a hole at 2" in the middle of the plates and your dielectric (which could be mica, glass, or any high enough energy dielectric to start. If you use a staticly charged plastic plate, be very careful, the output will attract the ions of the line and may belt you!..

I think if you add an iron rod through the holes and make a non conductive holder that will have a hole in it so the rod could stand in it, then the non conductive holder could be pushed into the ground, this would work. place a thick paper wrapping around the bottom of the rod and wind a coil of about 200 turns under the plate. The plate will need to be grounded on the bottom plate, and the top not connected.

The rod's coil will need to be grounded on one end and the other conductor will be connected to an analog voltmeter between the top coil connection and the grounded one. If this gives nothing, connect the top plate to the meter and the unconnectded coil winding.

If this doesn't work, you'll probably never get the field propagation correct. The capacitive plate and coil will need to be built to resonate at 60 hz to transfer energy from the power lines to the plate and coil. You also have no reference to ground from a delta overhead system, this means if there's only 3 phases and no neutral line, the energy across from phases to ground will not be existent and the energy will not be able to be induced.

When you run a line straight like this, you need a component to be energized at the end of it, like a choke or a very high voltage, very small capacitance cap. you would need an avramenko plug on both sides, one side would need to be grounded and a coil in series with the lower transmission line you build. Then the avramenko plug may release energy. If you connect one side to ground, the inductor or choke of a fairly high resistance will need to be wired in series between ground and the rest of the line, then an avramenko plug mounted to the other side, or, the line could be connected to a capacitive plate at the end of the rod used for the choke to collect the transmitted energy with the plates connected at a 90 degree angle to the choke or resonant inductor's core. Holes should be drilled through these plates and the capacitve nature of the plates should be calculated to ensure it will resonate at 60hz, otherwise you will NOT have a loose inductive coupling.

The plate could be used to draw dc energy from it, then transferred to ac with a battery and an inverter, so this may be a  wise try.

What I was saying before about the delta lines means that the delta system has no neutral and no ground. The energy returns on opposing phases because the coils of the generating equipment are tied together and placement of the coils are placed 120 degrees apart, hence 3 120 degree difference in phases. If the system is stepped up to 69kV, 115kV, 138kV, or 345kV, you should be able to see if there is a 4th line. The 4th line may indicate a grounded line (which is a static line), or, if you live in southern states or different countries, these may be grounded neutrals, or the lines could even be dc transmission lines which you could capacitively collect energy from, but I will warn everybody, be careful. The dc lines could strike and kill you. remember Tesla's statement about the blue streak of death!

Anyway, I have created two images, one I believe may collect small amounts of energy from both wye and delta transmission lines. remember, these are not designed to steal piower, they are for educational purposes only. I am not suggesting anybody go on the federally owned transmission line's right of way. It's a major charge and they would lock you up for sure. If you have land abutting the transmission lines, you may be able to collect something, but it shouldn't be anything that adds load to their lines if done capacitively, as well, the energy may if youre lucky light a few leds. If you make this to couple with the lines, you may be in for a big surprise, it may easily kill you and I am not suggesting anybody try this, not even from 200 feet away,. which is very possible. If tesla could run a car by driving within 1/4 mile of the transmissiobn lines, then we could somehow harvest the energy using a method similar to this!

GOOD LUCK AND PLEASE REMAIN SAFE USING ALL PROTECTIVE SAFETY EQUIPMENT. HIGH VOLTAGES CAN KILL WITH EVEN 1/2 AMP OF CURRENT, IN FACT, AT THIS LEVEL IT COULD BLOW OFF LIMBS ARE COMPLETELY BURN EVERYTHING OFF OF YOUR BODY. FLESH CAN INSTANTLY BURST INTO FLAMES, AND THERE WOULD BE NO WAY ANYBODY COULD SAVE YOU IF THE POTENTIAL IS TOO HIGH.

iF ANYBODY TRIES THIS, I SUGGEST YOU PUT THE DEVICE TOGETHER AND CONNECT A METER TO IT, THEN FROM A VERY LONG DISTANCE, BE SURE YOU CARRY IT WITH RUBBER GLOVES, WALKING TOWARDS THE LINES, WATCHING THE METER WHICH WILL MEASURE VOLTAGE ACROSS THE PLATES, AND ANOTHER METER ACROSS THE COIL FOR ADDITIONAL SAFETY.

PLEASE BE CAREFUL. SEE IMAGES BELOW.

Dezeinstein



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Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 30/11/2016 09:43:12
You are not going to get anywhere with small structures , low frequency's require large structures look at the antennas at droitwich or those used by the military to communicate with their submerged submarines.   
Title: Re: Can I harvest energy from overhead wires?
Post by: FREE ENERGY on 21/03/2018 18:24:37
Harvesting electricity from power lines
WARNING! Trying this experiment involves incredibly high voltages! Do not be a stupid scientist. Do not conduct this experiment on anything but calm days. Fasten and know where the antenna wire is at all times. There can be no large slack in the wire at any time. You must be at least 30 feet from the power line! Make sure you are an electrician, electrical engineer, ham radio operator, electrical student or have years of electrical experience. You must understand what is being presented here in its totality. Also, this is illegal! Conduct your experiment and then remove everything from the site.
If you run a single wire along a high voltage power line, (= or> 340KV), you will harvest a fair amount of voltage at micro amp levels. WARNING: KEEP AT LEAST 30 FEET FROM THE HIGH VOLTAGE LINE!! Use small gauge solid bare wire hung from fishing line for insulation and support. The longer the wire, the higher the voltage.  Use a fishing pole and weight to put up the wires in the closest branches along the right of way. Run your (antenna) parallel to the power line in the trees adjacent to one outer phase of the power line. The higher, the better. Run at least 200 feet of bare antenna wire. The wire must not touch any vegetation. WARNING, DO NOT TOUCH THE ANTENNA WIRE! YOU WILL GET SHOCKED!  Commercial rubber gloves work well for this. The goal is to present a minimum load to the antenna wire and to step down the electrostatically induced voltage using transformers. Provide a single or several 5 foot ground rods at your termination point for the transformer high voltage secondary return. Ground the antenna right away! We then connect a high voltage transformer secondary winding, (a ham radio plate transformer rated at 10,000 volts to 220 volts / 115 volts. A 15 kilovolt neon sign transformer is better). voila! You have usable power from the AC input terminals of that transformer. You have created a capacativly-coupled step-down transformer. Your final voltages off the low side of the transformer may be from 150 VAC to .5 VAC. Place a 4 watt, incandescent 120 volt light across the 120 volt terminals of the transformer. Ground the Antenna wire while you work until the transformer is installed and you are ready for power.  Removing the antenna clip from the ground rods allows the AC voltage to the light bulb. If the bulb pops, then you need still another step down transformer, say, 600 volts to 120 volts. Another transformer can provide more current. If the bulb does not light, (too much resistance), then remove the lamp and add a full wave rectifier and a 100 VDC, 10 microfarad capacitor. Measure the DC voltage. Can you run a small radio with this current? Charge a cell phone? Run a small ham radio? Run a small DC fan? Light up your campsite? The antenna by itself can also light up many florescent tubes at one time. Use the ground return for the other end of the florescent bulbs. Please be safe and work slowly!!
Title: Re: Can I harvest energy from overhead wires?
Post by: alancalverd on 21/03/2018 19:22:41
...and don't get caught. See reply #28 above. You may not receive a prison sentence for a first offence but theft of electricity is a crime for which you could forfeit any public service pension or membership of any professional institution - in other words, the guys who can best do this safely are the least likely to do it!
Title: Re: Can I harvest energy from overhead wires?
Post by: syhprum on 22/03/2018 05:36:22
This may well work out some of the most expensive power that you have ever obtained considering the cost of the equipment and the legal and physical dangers
Unless your antenna wire is very long the output impedance of the capacitive divider formed by the capacitance of the antenna wire to ground and the capacitance of the antenna wire to the high voltage line will be extremely high so although the open circuit voltage may well be 43KV as soon as you connect the transformer it will drop to a very low value.
If you must do this experiment connect the output of the antenna to a half bridge rectifier (using expensive diodes and use the resultant DC output to a chopper circuit a high frequency transformer) .
You would get cheaper power hiring an illegal immigrant to turn a hand generator.

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