A switch is simple: connect two pieces of metal together and bam! Except, it’s not that simple at high currents. How much current? Just about 400 car batteries worth would certainly cause some issues. This is the issue that [Technology Hobby] hoped to fix with his clever switch design.
While many content creators are great at finding or making high-current sources (looking at you, Styropyro), their switches can’t always hold up to the abuse. [Technology Hobby] found that many of the switches used by these creators had issues based on an inconsistent and limited contact area. Making a bigger contact patch is always fairly easy; keeping those contacts from skipping can be a bit more difficult.
[Technology Hobby] found success in making a V-shaped channel formed from separated contacts where a matching contact would bridge the gap between, completing the circuit. The construction of the high-current switch was simply done with a 3D printed frame filled with concrete for stiffness.
There’s a lot of fun with high current, but sometimes you need something more practical. For those needing some practical current supply, check out this retro-modern power supply!
I was on a kick for a while of seeing what sorts of interesting plasma I could make by zapping various things with a 900uF 3kV capacitor bank made with low ESR film capacitors so I also found myself in need of a switch that could handle obscene inrush current.
What I ended up doing was going to the hardware store and buying the burliest rat trap I could find and shaping its jaws to hold a couple of beefy copper busbars and it worked surprisingly well (there was still a little bit of ablasion but it closed fast and forcefully enough that it was greatly minimized).
For those interested in making a big, loud, and bright orange ball of plasma, I found that a brush made of carbon fiber tow just touching an aluminum can clamped to the other pole made a satisfying and repeatable bang louder than a .44 revolver. Also those hair-thin gold plated tungsten wires used to wind certain kinds of light bulb filament will flash to plasma in a pretty spectacular way =;-)
The problem is the Rebounding from amperage on the switch. When the amps get high enough the switch will not make good contact, at first and will bounce until makes contact. This leeds to arching, hot spots and destroying the switch. This wedge, if done correctly can mitigate the bounce. This also has some downsides with the wedge welding to the contacts, and there is no good way to open the switch.
This project was in response to StyroPyro’s 400 car batteries, which is a must watch. He used a hydraulic log splitter, and he still had really bad bounce when he was switch 160k amps, so he added another log splitter and then he had the issue of it being much slower, but it did help with bounce.
halfway there. now think of a system to open it again during load. that is always the most difficult part.
Since the switch does not have melting parts fusing, should be as simple as lifting the wedge up again. Also voltage is low enough that there should be no arcing.
StyoPyro himself commented some good things on the video. TLDR, he actually had considered a design like this but while it worked great at the currents tested here, StyoPyro was pretty sure it would have some significant drawbacks at the absolutely bonkers currents he was running.
Still very cool, and definitely useful in some applications!
Since this was in response to StyroPyro and his 400 car batteries, it should be noted that his voltage was 4 or 6 times greater, not to mention his amperage was waay higher.
Principal is sound, wedging/scraping action is in fact a superior connection.
I am very curious to see how it would respond to being scaled up. Also when he started scraping it with a chisel I wondered why he didn’t use a file.
400 car batteries. 160,000 amps? How would the switch not spot-weld itself shut? 12v may not arc much but those moments while it’s shutting or opening. Also what on earth are you people doing for hobbies my god.
I would work on spring mechanisms to open and close the switch very rapidly and firmly. Reducing the time when the contacts are allowed to arc is very important. Also, what about submerging the whole assembly in some kind of dielectric fluid?
Ahem…
https://en.wikipedia.org/wiki/Knife_switch
If this was used for the big battery bank, it would probably explode apart because of the concrete splitting too easily.
That was StyroPyro’s exact response – he was pretty certain this design would definitely weld itself together at his scale.
Also, StyroPyro’s YT channel is a neverending list of “how is this guy not dead?” lol
What’s the voltage on a recently opened switch when the circuit has non zero inductance.
IIRC he want’s a piece of zinc attached to one side near the circuit break point.
It will grab the arc and kill it.
Either that or pee on the arc.
I hope he tries or anyways or has a sponsor to do so. This is perfect science we have the hypothesis let’s test it –
Submerging the switchgear in oil is done in high power utility applications. All of this is century-old technology.
Seems like a variation on the old knife (“Dr Frankenstein”) switch, which is still in use in my 75 year old former school building, in the form of fuse/disconnect panels, some rated at 400 amps continuous current, with interruption ratings of several thousand amps. A little investigation into the oil-submerged, motor-driven switchgear used by the utility companies will save some re-inventing of the wheel.
Submerging the switchgear in oil is done in high power utility applications. And to get an idea of the spring mechanism, look inside an old “Square D” (TM) fuse/disconnect panel of the 400 amp variety. All of this is century-old technology.
Lightning bolt time
Reply not in intended thread again award
Oh, good, it’s not just me? I guess misery loves company. #OneOfUs, #OneOfUs
Have the “axe switch” on a big wooden dowel about 6′ long, you open the switch by lifting up the end of the dowel. Well if it’s not on fire.
an alexanderson alternator build originally had compressed air to blow out the arc of the contactors.
Don’t Whizz On The Electric Switch.
WTH? My comment was SUPPOSED to be a reply to HaHa, and the form even said “Reply to HaHa” as I was writing it. This is the exact opposite of the problem I’m used to having on Hackaday, where comments not intended as replies end up getting posted as replies to someone random. Now the reply nesting seems to have broken entirely.
The “report comment” links seem to have disappeared from all comments, too (no, I’m not suggesting that your comment needed it!)
The whole comments system here on HaD is janky, sad to say.
Some people like things that go boom
His log splitter switch is pretty good on its own, maybe it could be improved with better contacts similar to this one.
Photon Induction has some video’s about an antique “professional” switch for that sort of power. It’s original use was probably for battery banks for submarines some 100 years ago, but even the company who made the switch was not sure.
It sure was a beautiful switch. He does moderately abuse it, but I think it’s (sort of) justified for the youtube video, and I also don’t see much benefit in keeping the switch brand new.
I know, I know I’m being a Karen, but please, please say “current” not “amperage”
No, Marvin. They’re interchangeable. Gatekeep elsewhere.
StyroPyro used 2 log splitters. One to close the switch and the other to open it.
I’ve watched the full video and this one, and I think it has merit. However, scaling it up to the size that can handle these currents will be tough. I don’t have a quick DIY solution, but it is worth taking inspiration from (DC) contactors. Maybe close the contact in a bath of oil, but as the energy has to go somewhere it greatly reduces the trials per day.
The blowing stuff up is cool, but I would like to see a focus towards the high current magnetic effects. This requires a fully reliable system, where the subject is not the fuse. For example, by designing a reliable and cheap fuse. A steel rod of known diameter in a bucket of sand, for example. Then each text will have the same energy and duration to then compare magnetic effects.
Exactly what I was thinking
Cloning.
As soon as one dies, the next one is unfrozen from storage. Same with Colin Furze.
I think the goal with scraping was to reduce the high spots removing as little material as possible. A file risks taking away already leveled spots.
If all he wanted was flat matching surfaces he might have just been able to use abrasive grit and working the pieces together with the three flat method.
Tons of arching at 160k amps
AKA Sensationalized Stupidity
Content farming is why we have so many worthless YT videos.
A file wouldn’t get the surfaces that closely matching each other. Files are made for material removal, not creating perfectly flat surfaces. The kind of scraping he was doing gets the entire surface within less than 0.001”, it’s what they do on machine tool ways to get them absolutely flat.