Wireless power transmission

[Keego]

I'd like to transmit either 120V AC or ~10V DC through a 3cm steel plate. Based on the assumption that the steel is coated with a non-conductive material, would the easiest way to get power across the barrier be a small inductor?

I read a little bit about inductors a long time ago, but I don't remember anything now. Basically I remember that someone (telsa?) made an inductor which powered something across a room over the ambient air. I'd like to do that, only with steel in the way. What are your thoughts on wireless power transmission? Which would be the most efficient, AC or DC?

 

[Polyfluoroethylene]

You'd have to use AC. Have a large loop of wire on one side and one on the other. Power the circuit. If you're converting it to 10v DC afterwards, current loss will be minimal.


Personally, I'd just drill a hole.

 

[Woodchuck2000]

Your best bet is to get two horseshoe-shaped transformer cores and align them either side of the plate (with an appropriate number of windings on each) so that you have, effectively, a torus.

The steel shouldn't affect the magnetic flux too much and you'll get fairly effective transmission. It's probably well worth using this to modify the voltage rather than using a separate transformer later as it'll be more efficient.

 

[PowerEngineer]

How much power are you trying to transmit?

The arrangement Wookchuck describes is probably your best bet, but I have no idea where you'd find those horseshoe-shaped cores (with 120 VAC windings).

I'm thinking you really want to find some way to go around that plate rather than through it.

 

[Atheus]

Wouldn't a current be generated in the steel? Any conductor in a changing magnetic field will have a current induced right? And even if you don't fry something you will create a massive electromagenet and everyone will stick to the walls...

 

[The Boston Dangler]

Tesla in da house! I'm just curious, does the application include safecracking or slot machine hacking?

 

[Woodchuck2000]

Originally posted by: Atheus
Wouldn't a current be generated in the steel? Any conductor in a changing magnetic field will have a current induced right? And even if you don't fry something you will create a massive electromagenet and everyone will stick to the walls...

I'm fairly sure that the steel won't be magnetised by the process (although I may be wrong on that one).

It will, however, have a current induced which may cause problems if you're not careful!

 

[Bassyhead]

3cm is quite a distance, probably incur quite low efficiency.

 

[randalee]

Originally posted by: Woodchuck2000
Q]I'm fairly sure that the steel won't be magnetised by the process (although I may be wrong on that one).

It will, however, have a current induced which may cause problems if you're not careful!

A current induced into material creates a magnetic field (albiet it may be small). Using the right thumb rule (right thumb points the direction of the moving electron(s) ) the curl of your fingers points the direction of the curl of the magnetic field.

 

[the splat in the hat]

um well thats seems pretty straight forward if you look into history and the Nicola Tesla, , Tesla coil, eeerrrmmm AC would be the answer for power transmittion without wires, and its already been done, over 35 miles tested and yes it works very good and no we dont use this tech , westinghouse and general electric shafted the whole human race and put Ac power on cables instead , ie , the ac power system we use now, but yes power transmittion works and its been proven in the AC area......100 odd years ago.......

 

[Cashmoney995]

I thought the test in the desert just proved that we can cook hotdogs (gulp i mean humans) from 35 miles away.


Anyway, the one thing that is gonna bite you in the ass is intereference, be prepared for enough to block off your cell phone from getting on its network.

 

[alienal99]

i'm going to assume that the plate conducts because it is steel. Now here comes the real problem: Don't hook anything up to that plate that is more conductive than whatever system you use (i will agree that woodchuck's looks good). Where is this plate going to be?

 

[brentkiosk]

An AC carrying inductor placed near the steel plate will induce eddy currents in the plate (because it's a conductor). You will probably end up using quite a bit of your power in just heating up the plate with the eddy currents. As others have said, it really seems as if you should be trying to get wires around the plate if you can.

 

[PowerEngineer]

Originally posted by: the splat in the hat
um well thats seems pretty straight forward if you look into history and the Nicola Tesla, , Tesla coil, eeerrrmmm AC would be the answer for power transmittion without wires, and its already been done, over 35 miles tested and yes it works very good and no we dont use this tech , westinghouse and general electric shafted the whole human race and put Ac power on cables instead , ie , the ac power system we use now, but yes power transmittion works and its been proven in the AC area......100 odd years ago.......

Well, that is certainly "splat" (in or out of the hat)!

Lower frequency electromagnetic radiation is hard to direct without using a wire as a wave guide. The conspiracy theories that claim techology can be somehow suppressed for decades by an industry or a government should always be approached with skepitism.

:beer:

 

[Calin]

Originally posted by: Woodchuck2000

Originally posted by: Atheus
Wouldn't a current be generated in the steel? Any conductor in a changing magnetic field will have a current induced right? And even if you don't fry something you will create a massive electromagenet and everyone will stick to the walls...

I'm fairly sure that the steel won't be magnetised by the process (although I may be wrong on that one).

It will, however, have a current induced which may cause problems if you're not careful!

There will be some whirlwind-like currents in the steel plate - nothing really important, as every transformer core has them. The steel might remain magnetised, but during functioning, the alternative current will keep it in average in a demagnetised state.

 

[Calin]

Originally posted by: Bassyhead
3cm is quite a distance, probably incur quite low efficiency.

I don't know about crude steel magnetic properties, but it might have a capability to transmit magnetic field up to 1000 times as much as pure air. Have you seen the small gaps between magnetic circuit parts in electric engines? This is the very reason.
Even in the worst case, those 3cm of steel are better than 0.3mm or air.

 

[Calin]

Originally posted by: PowerEngineer
How much power are you trying to transmit?

The arrangement Wookchuck describes is probably your best bet, but I have no idea where you'd find those horseshoe-shaped cores (with 120 VAC windings).

I'm thinking you really want to find some way to go around that plate rather than through it.

Some bracket shaped cores could do fine (like this: [ || ] ), the || being the steel wall and the [ and ] the cores.