free power?

[keebler303]

ok i had a thought. the large high voltage power lines making up the power grid carry a large amount of current. so there is a big magnetic field around the lines.
would it be possible to construct a coil near some high voltage lines so that there was a current induced in your coil? just thinkin it would be cool to have a big coil in your garage and get your electricity for free. also would this be stealing? does that energy have to be replenished by the lines or is it just lost in space?
Thanks for fueling my curiousity.
Matt

[Al_The_Man]

Actually the current is brought down, by hiking the voltage up to 10's of thousands, voltage wise in order to lower the conductor size for transmission.
Even if you could do this safely, you would need a smaller version of those fenced in transformer compounds you see on the edge of urban areas, so one of these in your back yard would be a dead give-away.
There was a post on one site a while ago of the someone in Russia that had the same Idea, the rather gruesome photo showed a close up of the guy strung up at the top of a tower, his clothes had burned off and his flesh was cooked right through.
How do you think those crows keep their feet warm.
Al.

[keebler303]

i know the voltage is stepped up significantly but the current in them at 400,000V is still not negligable. i am wondering what amounts of energy could be had through this magnetic field at a reasonable distance. obviously the efficiency would be terrible because you have air carrying the field instead of ferrite etc. like a transformer and the distance is much farther than a transformer. but i would think with enough wraps of wire you could get some current going.
Matt

[gtd107]

This discussion reminds me of a physics experiment I did back in High School. On a humid night we ventured out close to the high powered lines and illuminated florescent lights by holding them above our heads. It was quite interesting. So I guess anything is possible. Although i am sure if you were ever able to harness the energy, the power company would cry fool that you are stealing from them even though they are raising my power bill 59% in May. I hate Utility Company De-regulation!

[Al_The_Man]

Originally Posted by keebler303 i would think with enough wraps of wire you could get some current going. Matt

Hypothetically speaking, if you are using inductive pick up, you would be operating as a current transformer, with a current transformer the current output is inversely proportional to the turns ratio, which I would think at that point make it totally non-practical, whats more, you would have to circle the high voltage conductor.
Al.

[paulC]

This does indeed take energy from the grid. You can compare it to a transformer that has no load on the secondary winding. There is little current draw from the primary of the transformer. As soon as you place a load on the secondary you draw more current on the primary.
And yes, it is stealing and there have been successful prosecutions against persons caught in the past.

Paul

[cwdance1]

I seen this on the news one time. The power company takes thermal images of its power lines from the air. They can see the hot spot if someone trys to steel power from them. Don't remember where or when I seen it but I remember thinking someone almost got away with it.

[CNCRob]

I was just wondering if anyone could explain to me or direct me to a link that explains it. I was wondering how a transformer can take electricity and make more volts after it has left the power plant. I was just wondering I was watching a show talking about it last night.

[Al_The_Man]

Voltage is only one component. Voltage can be 'Transformed' (up or down) at the expense of current so the power remains the same or slightly less after the transformation losses are taken in to account.
Al.

[keebler303]

power is the product of voltage and current
P=IV
so on the high voltage lines, lets say you have 200,000volts and a current of 100 amps.
P=IV
P=200,000x100=20,000,000watts
lets say the transformer has a 200:1 turns ratio
so you input 200,000 volts at 100 amps.
you get out 1,000 volts at 20,000 amps
P=IV
P=1,000x20,000=20,000,000watts
its the same amount of power you just exchange voltage for current and vice versa.

[CNCRob]

Does that mean that more voltage doesn't really mean more power? Sorry for the dumb questions, this has never really been one of my strong points.

[keebler303]

thats correct.
more voltage is only more power if the amperage doesn't decrease by as much as the voltage increases. from a cnc standpoint though, a motor will draw more current with more voltage so it will be more power. generally if you put more voltage into a device, it will be more power because the current doesn't decrease. the specific case we were talking was transformers where if the voltage increases the current must decrease.

Matt