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ultra high current source

ultra high current source

ultra high current source

(OP)
I am doing some experiments to measure magnetic fields and I want to generate a very high current 1kA for a brief period.  How could I do this with easily available components.
Could be AC. Mains power supply is 220V
Thanks.

RE: ultra high current source

Define 'brief'.

I saw an amateur mad scientist on TV that had a basement full of submarine batteries connected to a swinging bar that would short out to create ball lightning (or something that looked like ball lightning).

Also, Google can crushing and coin shinking.

RE: ultra high current source

Discharge from a large bank of capacitors.

RE: ultra high current source

I spelled 'shrinking' incorrectly (just in case anyone is tempted to cut&paste the terms into Google).

RE: ultra high current source

A current transformer energised from the mains on the secondary side would give you high current indefinitely on the primary. Any big toroidal transformer with a mains-rated primary and a single turn passed through it would give a similar effect to the CT - toroidals are available up to about 10kVA so you should be able to get a good few kA out of one into a single turn loop.
   

----------------------------------
  
If we learn from our mistakes I'm getting a great education!

RE: ultra high current source

1 kA isn't much. Any decent resistance welder produces 10 to 15 kA easily. A small one would probably suffice. Try any surplus store.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: ultra high current source

I agree with you Gunnar, I'm not sure how 1kA would even begin to be considered ultra high; lots of circuits run that much or more regularly.

RE: ultra high current source

What is your load impedance?  What do you consider a "brief period"?

RE: ultra high current source

How long does a ball of plasma last jimkirk?  

That reminds me.  I saw a ball of plasma yesterday that was fueled primarily by the last quarter inch of my needle-nose pliers and all the hair on the knuckles of both hands. I hate that old armor cabling, BX?

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: ultra high current source

Shorting a big NiCd cell will produce serious current.

Mike Halloran
Pembroke Pines, FL, USA

RE: ultra high current source

Shorting a big nicad will produce serious INJURY, to the cell or anybody near it.

RE: ultra high current source

Nah, it won't bother the cell, but it will melt your Crescent wrench.

Mike Halloran
Pembroke Pines, FL, USA

RE: ultra high current source

Don't try it at home!  smile

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: ultra high current source

For a few years, I had a NiCd battery in my car. A time-expired helicopter battery; drop in installation. As they say, 'Worked REAL good', even at -35C. Cold Cranking Amps appeared to be more-or-less infinite.

RE: ultra high current source

I wasn't intending to propose that one actually short the cell with a wrench, but to point out that even a single cell will feed a finite impedance (e.g. a contact or transistor and a fat wire) with substantial current.

Mike Halloran
Pembroke Pines, FL, USA

RE: ultra high current source

alansimpson, please describe your requirements exactly so we can be helpful.  Specifically, we need to know how much current, for how long.

Please be advised that you are asking for a dangerous setup, and you should not try any of the previous suggestions without full working knowledge of what you are doing.  In other words, this kind of stuff WILL kill you if you don't know what you're doing.

RE: ultra high current source

A long time ago, I did a short-circuit current test with a DVOM (10 amp input) across an alkaline D cell and saw only about 2A. I just repeated the test (just now) with an alkaline AA cell, and got 8.5A (wow!).

Maybe battery chemistry and design has improved over the years, or maybe the newer meters have a lower voltage drop across the 10A input.

RE: ultra high current source

In the interest of safety, I do not recommend shorting out batteries with the 10A input of meters. Please do not try this at home. All sorts of bad things might happen.

RE: ultra high current source

It's my understanding that shorting a LiIon cell is a worse idea than shorting a NiCad.. (Worster?) LOL

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: ultra high current source

(OP)
1kA for a period of less than a second would do.  
I am aware of dangers and will be taking suitable precautions.  
Your concerns for my safety are appreciated.

RE: ultra high current source

What is the resistance you want to apply this 1kA to?

Say it's 0.001 ohms, you need to supply 1VAC so ScottyUK's suggestion or some slight variation is good. Basically, a 120V:1V step down transformer so you apply 8.3A to the primary and get 1V @ 1000A on the secondary.

Now say it's 0.5 ohms, then you need 500V and 500VAC @ 1000A  certainly can't be sourced from a wall socket (or even from many services).

RE: ultra high current source

http://www.myelectricengine.com/
This guy shows you how to build the cap. bank.
Itsmoked, he also has a good section on plasma arcs.

RE: ultra high current source

That capacitor bank reminded me of a couple of machines I built 25 years ago to magnetize plastic sheet magnets like you find on refrigerators. Those welding cables jumped every time it fired and that was every 2 seconds.   Used a mercury filled Ignitron to fire it.  Seemed like every week the tube would short out.  Then we would turn it upside down and shake it to collect the plated mercury.

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