Method to create a high current and low voltage

  • #1
Siddhartha Peri
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How would I be able to produce a circuit that produces a very high current at a very low voltage? Would it be considered a reverse Tesla coil?
 

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  • #2
berkeman
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How would I be able to produce a circuit that produces a very high current at a very low voltage? Would it be considered a reverse Tesla coil?
Welcome to the PF. :smile:

Are you wanting AC or DC high current capability? What level of current are you asking for? Can you say what the application is?
 
  • #3
Siddhartha Peri
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Welcome to the PF. :smile:

Are you wanting AC or DC high current capability? What level of current are you asking for? Can you say what the application is?

DC high current capability, 200 million amps, research study
 
  • #4
berkeman
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DC high current capability, 200 million amps, research study
Woo doggies! That's a lot of amps. How long do you need to sustain this level of DC current? How close is the nearest power substation?
 
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  • #5
Siddhartha Peri
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Woo doggies! That's a lot of amps. How long do you need to sustain this level of DC current? How close is the nearest power substation?

I believe for 0.18 seconds and the nearest substation is 30 miles away.
 
  • #6
berkeman
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I believe for 0.18 seconds and the nearest substation is 30 miles away.
Your Profile page says you are in Undergrad right now. Do you have an advisor for this research work? What is your budget for creating this facility?
 
  • #7
Siddhartha Peri
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Your Profile page says you are in Undergrad right now. Do you have an advisor for this research work? What is your budget for creating this facility?

Yes I do have an advisor and we have a budget of 250k.
 
  • #8
berkeman
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What degree are you pursuing? Have you looked into charging a (very) large capacitor bank? What capacitance would be needed to store that kind of energy?
 
  • #9
Baluncore
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How would I be able to produce a circuit that produces a very high current at a very low voltage?
What is a very low voltage? Is it 20uV, 1V or 50V ?

Where will the 200 million amp current flow? That will identify the load voltage, and so the energy storage requirement.
How might you switch such a current?

Are you making a magnetic field using a Bitter electromagnet? If so, have you considered the implications of inductance in the circuit?
There are also Marx impulse generators that produce a circular current rather than a high voltage.

You must explain the application so we do not have to guess which answers might be most appropriate. We probably know many of the possible answers to your open-ended question.
 
  • #11
jim hardy
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?
upload_2018-8-1_8-51-5.png
?
 

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  • #12
Baluncore
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Yes I do have an advisor and we have a budget of 250k.
Is that budget in joules, Rupee, Yen or US$?

We cannot help you if you are unable to communicate.
 
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  • #13
Windadct
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haha - I'll just leave THIS here...
 
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  • #14
skeptic2
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In the 1970s I worked at a plant installing radio controls on the cranes over aluminum potlines. Aluminum is made by passing a high current through a mixture of bauxite and an electrolyte. In one plant there were 8 potlines, each running about 200,000 amps. The pots are in series with about 5 volts across each one and 750 volts across the whole line. The conductors produced about 200 gauss which was enough to saturate the powdered metal cores in the radio receivers and detune them. And yes, this plant was very close to a power station.

As such I am very skeptical of the claim that 100,000 amps is by far the highest current ever produced in the world. By the way isn't RT the name of the magazine that used to be called Russia Today?
 
  • #15
Baluncore
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As such I am very skeptical of the claim that 100,000 amps is by far the highest current ever produced in the world.
I think the 100,000 amp record was only for a superconductor.
 
  • #16
magoo
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A railgun uses a principle where they charge up a fairly capacitor bank and then discharge it at high current when they want to fire it.
 
  • #17
jim hardy
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Current density is the limiting factor.

For more reasonable currents in a household experimental environment ,
buy a secondhand soldering gun to take apart and play with.

upload_2018-8-3_12-56-58.png


low voltage high current out of those two stubs.

Junk shops are full of them, around here they go for five bucks..
 

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  • #18
dlgoff
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low voltage high current out of those two stubs.
Heck. I still use mine.

Junk shops are full of them, around here they go for five bucks.
I really need to visit that junk shop with a pocket full of money. :approve:
 

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  • #19
dlgoff
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The conductors produced about 200 gauss ..
I thought you were going to say the conductors were jumping around causing damage. :olduhh:
 
  • #20
Baluncore
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High currents are invariably used for high magnetic fields. The strongest magnetic fields I believe are created using optimised Bitter coils with an explosive compression. The energy involved in 200Mega-amp with a 1 volt drop for 0.2 seconds is equivalent to 40kg of TNT.

It seems the OP has simply reversed the voltage and current specifications of a Tesla coil or lightning strike without considering the circuit impedance R+jX, energy, or the square law. I do not believe the OP is really serious about the question.
 
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  • #21
Svein
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In the early 1980s I was working in an industrial research institute. Several projects had to do with new and non-standard ways of doing things related to the offshore oil business. One project in particular was about detecting internal cracks in subsea pipes using magnetic field measurements. As far as I remember, the voltage used to drive the current had to be below 1V, otherwise the sea water would start to conduct. Since such a pipe is large, there would be very little resistance between the two voltage supply points. Therefore: Low voltage, high current.

I may not recall correctly, but my mind suddenly pictured 0.85V and 100A.

No, I do not know what happened to that project.
 
  • #22
jim hardy
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Heck. I still use mine.
Me too. Great for car wiring - trailer lights, repairs,
and if you replace the tip with a coil of #12 solid you have a demagnetizer for hand tools tape heads and the like. . Worked great when an unshielded subwoofer underneath my Sony Triniton turned that corner of the screen purple. (today's flatscreens seem unaffected )

Will pick one up for you.

old jim
 
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  • #23
gleem
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CERN's record is only 20 Kamps but that is for a fairly long superconductor. https://home.cern/about/updates/2014/04/world-record-current-superconductor
Isn't it true that the magnetic field that the superconductor creates will quench the superconductor at some critical field.strength limiting the maximum current?

What is the object of OP experiment?

For 200 Mamps an ordinary conductor would have to be short with a large crossectional area. If you do the calcs a 1m long by 10 x10 cm copper buss it would probably explode with that current flowing for a time significantly less than 0.18 sec.

The energy released using E = I2Rt is about 12 GJ for the aforementioned buss would be equivalent to about 1.5 tonnes of TNT

The energy involved in 200Mega-amp with a 1 volt drop for 0.2 seconds is equivalent to 40kg of TNT.

To drive 200 Mamps with 1 V you would need something like a 1 meter cubed block of copper.

Think about it can you deliver that amount of energy in that time frame from any reasonable physical setup. you would blow up the transmission line.

Yes I do have an advisor and we have a budget of 250k.

Not sure about the adviser.
 
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  • #24
berkeman
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What is the object of OP experiment?
Right now it looks like he was just trolling. Still, it generated an interesting discussion about high-current applications in the real world (not his world)...
 
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  • #25
Baluncore
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I may not recall correctly, but my mind suddenly pictured 0.85V and 100A.
When a welding level regulated current passes through a poor weld, there is a change in the flow path of the current that can be detected by magnetic powder, or mapped with hall effect sensors. That technique of crack detection has been used for many years.
 
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  • #26
jim hardy
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FWIW

Our main generator armature current was around 20 kiloamps. The armature conductors were made of square strands stacked together and insulated from one another so magnetic effects wouldn't push all the current out to the periphery by 'skin effect'. They left lengthwise internal passages through which hydrogen gas flows for cooling.

Haven't found a picture yet.

old jim
 
  • #27
Rive
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Haven't found a picture yet.
A bit of an advertising (sorry), but the main point can be seen here.
 
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  • #29
Asymptotic
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Me too. Great for car wiring - trailer lights, repairs,
and if you replace the tip with a coil of #12 solid you have a demagnetizer for hand tools tape heads and the like. . Worked great when an unshielded subwoofer underneath my Sony Triniton turned that corner of the screen purple. (today's flatscreens seem unaffected )

Will pick one up for you.

old jim
Another useful repurposing is to supply the soldering gun with a variac, add an ammeter, and use it as an adjustable high current source to check whether motor starter thermal overload relays trip at their rated values. It can also be used to check the calibration of, and set up AC current to 4-20 ma/0-10V signal conditioners.
 
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  • #30
James Demers
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Current density is the limiting factor.

For more reasonable currents in a household experimental environment ,
buy a secondhand soldering gun to take apart and play with.

View attachment 228778

low voltage high current out of those two stubs.

Junk shops are full of them, around here they go for five bucks..
Waitaminnit .... how did my soldering gun end up into that junk shop?
 
  • #31
essenmein
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Another interesting way to make large currents at low voltage and DC is a homopolar generator, bonus you get mechanical energy storage in the form of a fly wheel.

I've read about people making spot welders and other high current things with by re winding micro wave transformers, single turn secondary type thing.
 
  • #32
essenmein
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A bit of an advertising (sorry), but the main point can be seen here.
Big boy stator!

It always impresses me seeing larger than life versions of things, whether its power plant e machines where you can walk around inside the stator or ship diesel engines where the ratchet to remove the cylinder head bolts is hydraulically powered and has its own crane.
 
  • #33
.Scott
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DC high current capability, 200 million amps, research study
Let's do total cross-sectional current:
I'll build a toroid of 10 gauge magnet wire; inside diameter 2 feet; outside diameter 6 feet; thickness 1 foot.
So the windings will have 2 square feet of cross section. For 10-gauge magnet wire, that's about 15000 turns.
Each turn will average 4pi feet - so 188,500 feet. For that quantity, I think I could get the wire at $0.40 per foot. So $75,400.
The resistance across this toroid will be very close to 188.5 ohms.

If I was to do this with a single toroid, the current would need to be 200Mamps/15000 = 13,333 amps.
But my budget is $250K, so I can stack three of these. Getting the current in each to 4,444 amps. So I will need 838KVolts at 13,333 Amps for 180msec to power this. 11.2GW for 180msec = 2G joules. (560 KWhours)

The copper is 14grams/foot. So total weight of all three toroids would be 3*14*188,500 grams = 7.92Mg.

Taking the thermal mass (or density) of copper at 38.46J/gC. We have a temperature rise of 2GJ/(38.46J/gC * 7.92Mg) = 6.6 degrees Centigrade.
So we won't met the toroids.

Average price for electricity in the US is $0.12. So the energy cost is $67.

I still have $25000 left in my budget to find a way to go from AC to 838KVDC.

When I worked in Ayer, MA, there was an AC/DC power converter next door for electricity coming in from Canada. It was basically a 5-acre electric circuit.
He needs to borrow that for 180msec.
 
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  • #34
GTrax
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I have to try and look it up again, but years ago I was aware of a 3-set of laminated composite flywheels, these being series-connected homopolar generators which were wound up to speed, either from grid energy, or from diesel generator sets. Then, the high current pulse was made by switching the generators into the load, all in an effort to make an extremely strong pulse magnetic field for research. The storage flywheels weighed tons, supported on air bearings. 1.6 million amperes is a number that I remember.

Today there exists the remains of a 500 MegaJoules homopolar generator used along with a 7.7 MegaElectronVolts cyclotron operated at the Australian National University College of Physical and Mathematical Sciences back in the 1950's. It never completed the original mission, but was used for many other research projects.

At a more modest level, I have a PDF describing use of a homopolar generator to weld railway line, and yes .. it is old, from 1970's 1980's era. At 4.1MB, it is too large to upload, but it can be found at ..
https://repositories.lib.utexas.edu/bitstream/handle/2152/33237/PN_095_Aanstoos.pdf;sequence=1
Apparently 575kA pulse for 3.2s
 
  • #35
trainman2001
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When they were running the Tokamak fusion reactor at Princeton University, they had two 100 ton (not sure about the weight) flywheels in the floor that were brought up to speed and then unloaded through the reactor. Their current creation was enormous (again, don't know the exact number), but was told by the tour guide that without the flywheels, the load would have blacked out Northern NJ.

Here's a description of the motor/generator set that produces the power. It seems very large, but I'm not really able to figure our what the amperage would be on discharge. Perhaps, one of our esteemed readers can decipher it. It gives power, and frequency, but I don't see the output voltage which I believe you'd need to figure amps.

"This paper provides a general description of 475 MVA pulsed motor generators for TFTR (Tokamak Fusion Test Reactor) at Princeton Plasma Physics Laboratory. Two identical generators operating in parallel are capable of supplying 950 MVA for an equivalent square pulse of 6.77 sec and 4,500 MJ at 0.7 power factor to provide the energy for the pulsed electrical coils and heating system for TFTR. The description includes the operational features of the 15,000 HP wound rotor motors driving each generator with its starting equipment and cycloconverter for controlling speed, power factor, and regulating line voltage during load pulsing where the generator speed changes from 87.5 to 60 Hz frequency variation to provide the 4,500 MJ or energy. The special design characteristics such as fatigue stress calculations for 1,000,000 cycles of operation, forcing factor on exciter to provide regulation, and low generator impedance are reviewed."

I have a resistance soldering system that produces up to 100 amps at 3 volts.
 

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