RCBO circuit breaker teardown and extreme overload test - Page 1
Forum section: electronics / general

author: MatthewEveritt
author_rank: Unknown
timestamp: February 19, 2016, 03:47:45 pm
content: Oops.An interesting video without the testing, and brilliant with it. Glad you were standing where you were, that could have been nasty.

author: Cliff Matthews
author_rank: Unknown
timestamp: February 19, 2016, 04:05:58 pm
content: Spectacular! Well done Mike, I'm glad things went the way they did. Better the shrapnel took out the lights and not you.Can you tell us how far away you stood at surge time?

author: bktemp
author_rank: Super Contributor
timestamp: February 19, 2016, 06:00:35 pm
content: Great video! I didn't expect the coil doing such a damage. How much energy did you put into the breaker?Nice to see you still have your old stuff. Does your the highspeed camera still works?Does the orientation affects the operation? Most circuit breakers are mounted vertically, with the arc path being above the contact. Maybe this helps guiding the arc into the quenching block.Seeing an opened circuit breaker tripping+arcing at highspeed would be great.Discharging some large electrolytic caps charged to only 300-400V via a small inductor into the circuit breaker is probably the easiest way to generate an arc without blasting everything to pieces.

author: HP-ILnerd
author_rank: Frequent Contributor
timestamp: February 19, 2016, 09:30:55 pm
content: Holy crap!That coil...hard to believe how deformed and work-hardened the wire was!Amazing stuff, Mike!

author: Monkeh
author_rank: Super Contributor
timestamp: February 20, 2016, 05:16:25 am
content: I think we should all have gained a new respect for the power of a distressed solenoid out of that. Yikes.

author: Lightages
author_rank: Unknown
timestamp: February 20, 2016, 05:53:43 am
content: Nice video and fun and your expense! One thing. The breakers are made to be mount vertically so the arc heats the air and causes it to rise through the quencher. When you had the breakers mounted horizontally the heat convection could not take effect.

author: Monkeh
author_rank: Super Contributor
timestamp: February 20, 2016, 05:59:16 am
content: Quote from: Lightages on February 20, 2016, 05:53:43 amThey can be and are regularly installed horizontally. Convection is not employed.

author: Lightages
author_rank: Unknown
timestamp: February 20, 2016, 06:12:58 am
content: I would love to be proved wrong. I often am.

author: SeanB
author_rank: Super Contributor
timestamp: February 20, 2016, 09:33:48 am
content: The reason the arc moves is the magnetic field of the current. This pushes it along the conductor ( Right hand rule, current, magnetic field of this current and the resultant force pushing it out further) till it hits the arc quencher which cools the gas down till it no longer conducts and breaks the arc. Some breakers here have the arc chamber at the bottom, facing down, and they do break the arc.DC breakers have to have a much longer arc path, plus breaking the path into multiple channels with insulating dividers to lengthen the arc plasma channel, so that they can break a DC arc safely. That is why you see many switches with low DC voltage and current ratings compared to the AC rating, so the arc channel will break the DC arc safely. Typically 250VAC 10A is derated to 30VDC 3A.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 20, 2016, 10:33:45 am
content: Quote from: Lightages on February 20, 2016, 06:12:58 amThis is a typical layout of a 3-phase fed distribution board in the UK

author: SeanB
author_rank: Super Contributor
timestamp: February 20, 2016, 10:50:47 am
content: Quick one I did a while ago on an old breaker. It did not survive either, but did not fail as spectacularly.Time for Mike to get a 63A standard breaker and see if it will also explode, and then to get a large high breakin capacity one off eBay and see if it will survive as well.Something from this or grab similar at the local wholesalers or scrapyard.http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=15&Amperage%2520Rating=100&LH_ItemCondition=10&_nkw=circuit%20breaker&_dcat=104232&rt=nc&Voltage%2520Rating=240%7C480%7C480%252F600%7C%21&LH_PrefLoc=5

author: Lightages
author_rank: Unknown
timestamp: February 20, 2016, 11:09:59 am
content: Quote from: SeanB on February 20, 2016, 09:33:48 amI might be thinking incorrectly right now, but that doesn't make sense to me. If it is an AC current, shouldn't the arc go both ways as the current flips then?

author: Lightages
author_rank: Unknown
timestamp: February 20, 2016, 11:12:11 am
content: Quote from: mikeselectricstuff on February 20, 2016, 10:33:45 amOK, I am most probably wrong, but I still don't understand what forces are at work to move the arc towards the quencher.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 20, 2016, 11:30:24 am
content: I think it's probably mostly just air expansion within the confined space, which forces it towards the only exit, which is through the plates

author: Ian.M
author_rank: Super Contributor
timestamp: February 20, 2016, 12:19:59 pm
content: Its all to do with the shape of the current path through the conductors and the initial arc. Because there is a curve or bend, the magnetic field is concentrated on the inside of the bend. The Lorentz force on the arc then forces it radially outwards because, unlike a solid conductor, the plasma has no tensile strength to resist it. Its basically the same effect that tore the coil apart during the severe overload.

author: SeanB
author_rank: Super Contributor
timestamp: February 20, 2016, 12:30:16 pm
content: Thanks Ian, and with AC or DC the force is the same, as the force depends on the magnitude of the current, and both the current flow and magnetic field change with each half cycle with AC, giving a force in the same direction in each case. This moves the arc to wanting to be as close to a stright wire along with the conductors as possible, and as the wire does not move ( for low current) the arc has to move to try to maximise coil cross sectional area and thus lowest inductance.

author: Carrington
author_rank: Super Contributor
timestamp: February 20, 2016, 09:07:06 pm
content: https://youtu.be/gOUSDDLKICk?t=1671OOPS! LOL...Awesome, as always.

author: Synthetase
author_rank: Regular Contributor
timestamp: February 21, 2016, 01:46:48 am
content: On the subject of slow motion, what happened to that Kodak slow motion camera you tore down?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 21, 2016, 02:08:06 am
content: Quote from: Synthetase on February 21, 2016, 01:46:48 amStill have it - as I said in vid, it wasn't fast enough to capture anything useful - all you see is 1 frame of flash & it bouncing around afterwards

author: Synthetase
author_rank: Regular Contributor
timestamp: February 21, 2016, 04:27:00 am
content: Quote from: mikeselectricstuff on February 21, 2016, 02:08:06 amOh right. I thought you were talking about your normal camera at that point.

author: peter.mitchell
author_rank: Super Contributor
timestamp: February 21, 2016, 06:55:16 am
content: i think an arc welder would be perfect for demonstrating the arc quenching part of the breaker.

author: Cliff Matthews
author_rank: Unknown
timestamp: February 21, 2016, 01:33:30 pm
content: Maybe get Edgertronic to loan out a sample hi-spped cam? For the publicity.. (they sell at $5k USD, but ~18,000 FPS sounds like it would have filled the need)http://edgertronic.com/camera/#the-edgertronic

author: Stonent
author_rank: Super Contributor
timestamp: February 21, 2016, 08:13:42 pm
content: The clunk and hum of the destructomatic charging gave me Photonic Induction flashbacks.That would be an interesting video series, Mike heads to Gravesend to destroy some things with Photon.

author: orion242
author_rank: Unknown
timestamp: February 22, 2016, 12:56:04 am
content: Pretty impressive little device. Found the details on your site. Nice video, thanks!

author: dexters_lab
author_rank: Unknown
timestamp: February 23, 2016, 04:40:13 pm
content: fantastic video mikewas your destruct-o-tron turned all the way to 3kj when you blew the breaker?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 23, 2016, 04:55:57 pm
content: Quote from: dexters_lab on February 23, 2016, 04:40:13 pmPretty much

author: Seekonk
author_rank: Super Contributor
timestamp: February 23, 2016, 06:57:09 pm
content: "what forces are at work to move the arc towards the quencher. "from Gaseous Conductors by James Dillon Cobine, a book that everyone should own.

author: dexters_lab
author_rank: Unknown
timestamp: February 23, 2016, 10:59:28 pm
content: Quote from: mikeselectricstuff on February 23, 2016, 04:55:57 pmlol nice, i think i would have done it outside, must have gone off with quite some volume! i use ear defenders when firing the magstim and thats only a lame 0.26 J!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 23, 2016, 11:29:52 pm
content: Quote from: dexters_lab on February 23, 2016, 10:59:28 pmproblem with outside is scaring the neighbours...

author: Monkeh
author_rank: Super Contributor
timestamp: February 23, 2016, 11:34:34 pm
content: Quote from: mikeselectricstuff on February 23, 2016, 11:29:52 pmThey'll get used to it. Or you'll get very friendly with the local rozzers..

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 23, 2016, 11:37:52 pm
content: Quote from: Monkeh on February 23, 2016, 11:34:34 pmWould rather not.Again.Last time, the combination of my 1MV Marx generator and an ungrounded garage door made my alarm system send a panic signal.

author: dexters_lab
author_rank: Unknown
timestamp: February 24, 2016, 10:12:38 am
content: Quote from: mikeselectricstuff on February 23, 2016, 11:29:52 pmfair point, it gets noisy around me, it's not a quiet street so less of an issue

author: Carrington
author_rank: Super Contributor
timestamp: February 24, 2016, 06:52:29 pm
content: In Spain we don't need build a "destruct-o-tron", the electric company does it for us.After destroying a lot of electrical goods, along several streets, they just said: I didn't do it! And that's all, problem solved!This is what got into one of the sockets, and remained for more than 5 consecutive hours.

author: Monkeh
author_rank: Super Contributor
timestamp: February 24, 2016, 06:53:42 pm
content: Well they didn't do it! The guy who walked off with the copper did.

author: Carrington
author_rank: Super Contributor
timestamp: February 24, 2016, 06:58:55 pm
content: Quote from: Monkeh on February 24, 2016, 06:53:42 pmYeah, something similar.

author: Lightages
author_rank: Unknown
timestamp: February 25, 2016, 03:38:35 am
content: Quote from: Carrington on February 24, 2016, 06:52:29 pmAnd this is exactly why people need to pay attention to proper safety ratings on meters!

author: Monkeh
author_rank: Super Contributor
timestamp: February 25, 2016, 03:41:25 am
content: Just a lost neutral, not that horrific.

author: Carrington
author_rank: Super Contributor
timestamp: February 25, 2016, 04:59:14 pm
content: Quote from: Monkeh on February 25, 2016, 03:41:25 amThat was exactly what happened, but... Who cut the neutral? And why?In addition, why the electric company took longer than 5 hours to react (cutting off the supply)?I got in touch through their emergency number, to alert about the problem, as soon I noticed what was happening. And the operator did not believe me!Well, it might be reasonable, maybe they have many calls from trolls, but later I learned that many of my neighbors also called warning of the problem.So... Lesson learned! After that, I added under/over voltage and surge protection to the electrical installation.Unfortunately when the electrical installation was made these protections wasn't mandatory, so nobody installed one.

author: Monkeh
author_rank: Super Contributor
timestamp: February 25, 2016, 05:27:44 pm
content: Quote from: Carrington on February 25, 2016, 04:59:14 pmCopper thief. Happens a lot.

author: Carrington
author_rank: Super Contributor
timestamp: February 25, 2016, 06:56:50 pm
content: Quote from: Monkeh on February 25, 2016, 05:27:44 pmI hope that the next time they make a mistake and steal the phase line.

author: Brumby
author_rank: Unknown
timestamp: February 25, 2016, 10:58:58 pm
content: With that sort of phase imbalance, even chopping the neutral could cause a bit of a tickle if they weren't careful.Quote from: Carrington on February 25, 2016, 06:56:50 pmI knew a guy who used to work for the section of the energy supplier in Sydney that looked after poles and wires - and he told me of someone who did just that one night. Not sure whether it was 3.3kV or 11kV - but not pretty apparently.