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1000volts 1000amps

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Microwatt

Sun May 22 2011, 05:58AM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
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Posts: 224

would it be possible to generate this on a sustained basis in a garage? what would the arc look like? not a serious question

magnet18

Sun May 22 2011, 06:09AM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
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Posts: 624

Maybe, if you wire the as many identical transformers as possible from each room in parallel, and then channel that into your garage and parallel it all.

That would be a freaking awesome arc, probably capable of being drawn out a few feet at least.
Don't try it while you're in the room, as it would kill you in a heartbeat. One. heartbeat.

Microwatt

Sun May 22 2011, 06:40AM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
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I was thinking about a homopolar flywheel generator. Build something that can be spun to 10000rpm and suddenly attach a magnetic field and drain power. The military uses devices like this to make multigigajoule pulses.

Mattski

Sun May 22 2011, 07:04AM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

On a sustained basis? That's 1MW and even a beefy 220V 100A feed to your house is a measly 22kW. It would also be over 3 million BTU/hour, which will get your garage toasty nice and quick :)

With the right capacitors or a compulsator, 1MW pulsed power for very short times is quite reasonable. I imagine it would look something like a short lightning bolt.

Dr. Slack

Sun May 22 2011, 08:19PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Sustained?

Sustained for 1uS, 1mS, 1 second, 1 day?

A car battery is good for 1kW or thereabouts, so you'd need 1000 of those if your goal was 10 minutes +.

A photoflash capacitor can do 300A from 300V for a while (a very short while, you do the math) so only 11 of those (say 12 as 4 series 3 parallel strings) would get you 1MW.

But unless you know a nice maintenance man at your local factory or shopping mall who'll let you play with the 11kV incoming on a quiet Sunday afternoon, you won't be getting it from the mains.

Steve Conner

Sun May 22 2011, 09:43PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

That would be nice as in insane, I guess. I've been around these 11kV switchboards and the last thing you feel like doing is playing with them.

As pointed out in the toasty garage comment, pulling a megawatt arc wouldn't be that different in terms of thermal impact to being trapped in a burning house, indeed it would probably set your garage on fire.

Marko

Sun May 22 2011, 10:22PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi guys,

Well, I'm not sure if a 1kV 1000amp arc would last to be drawn too long, since it's pretty low voltage it would tend to expand violently due to magnetic forces and self extinguish. The dissipated power would never be 1MW, but much less, if the current is limited to just 1000amps. It would be sort of like a large welding arc and probably not exactly in garage burning or personnel burning category.

This is a classic demonstration of a DC arc within this ballpark, 3kV and 500A.

Avalanche

Sun May 22 2011, 10:54PM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

I was thinking of the best way to do this, and it certainly is possible to do within a garage - budget depending!

Firstly, you would need to hire 5, or lets say 6 large 200kVA generators. It's doubtful you'd be able to get this many at once without a lot of notice, so I'd recommend speaking to a local hire company about your requirement. The next thing to do is to get a permit from your local council to have the generators located at your house - this may be difficult, and you may need to move house to somewhere more remote and with a bit of land. Proper planning would be essential, as would careful project management and budgeting. Ensure that the fuel tanks are all full when the generators arrive, and note that you will be subject to a nasty penalty if the generators are not re-fulled before they are collected at the end of the experiment!

The tricky part is combining the output of the generators - I figured the easiest 'off the shelf' way, being as they will be three-phase gensets would be to have 5 (or 6) custom wound transformers (star to delta) and then rectify and combine the individual DC outputs with large three-phase rectifiers, making up 1kA 1kV. Three-phase power is constant when compared to rectifying single phase, so the fact that the gensets would probably be running out of phase wouldn't matter so much.

Striking the initial arc would put an enormous sudden load onto the gensets, but in my experience they seem to be able to cope with this very well - some testing I did at work a couple of years ago involved throwing a resistive load of 170kVA on and off a 200kVA diesel genset - and surprisingly it didn't bother it at all! There was the odd bit of over and undershoot as expected, but impressively the engine hardly noticed!

Now, for the arc itself - this is the tricky bit. Maintaining 1MVA in the arc itself would be difficult - in terms of impedence matching. It's more likely that most of the power would be being burnt in the transformers, so you would be safe in the garage with the arc. You can adjust the length of the arc, but eventually it will extinguish

not sure about how to regulate the arc, without modifying (and combining) all the PID controls in the generators to somehow take feedback from the arc itself.

Anyone have any better ideas?

Zum Beispiel

Mon May 23 2011, 12:16AM

Registered Member #514 Joined: Sun Feb 11 2007, 12:27AM
Location: Somewhere in Pirkanmaa, Finland
Posts: 295

I'd say a whole bunch of car batteries would be the way to go. A hundred in series will give circa 1400V open circuit with over 500A short circuit. Put a a few strings in parallel and strice an arc. A millisecond later everything will be on fire and you will feel very silly (but not for long, what with the fire and everything).

Microwatt

Mon May 23 2011, 02:54AM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224

The battery idea is probably the cheapest since you could get junkyards ones for 5.00 apiece and even less if you buy in bulk. 750kw for 500 bucks sound pretty cheap?

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