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Blowing up a 5000 amp fuse

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  • Michael Edwards
    replied
    Originally posted by Guido View Post
    Check out YouTube: ‘LA bomb squad explosion’
    That was an epic blunder. All of that money spent on equipment and they just took a guess on the weight of the explosives. Another couple hundred bucks for a scale and this would not have happened.

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  • Doozer
    replied
    Originally posted by Arcane View Post

    Just because he's an EE doesn't mean he has a clue about safety. **** happens and you have to take that into account when you are dealing with the energy he is. You simply can't work on the premise of "Nothing can go wrong."
    why-does-it-matter-to-you?
    If he blows himself up, it will likely be documented on video.
    Perfect training video footage.

    -D
    Last edited by Doozer; 09-20-2021, 07:08 PM.

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  • Arcane
    replied
    Originally posted by I make chips View Post
    I sold induction equipment up to 6 megawatts. Over the years I heard a few horror stories of competitors equipment that went bang. Like almost vapourising people type of bang.
    Fortunately our stuff was too well protected to let major smoke out.
    A lot of people don't realize that an electrical arc can kill you without electrocuting you; the heat alone is enough. The electrical utility I worked for had training sessions where such information was disbursed.

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  • I make chips
    replied
    I sold induction equipment up to 6 megawatts. Over the years I heard a few horror stories of competitors equipment that went bang. Like almost vapourising people type of bang.
    Fortunately our stuff was too well protected to let major smoke out.

    Leave a comment:


  • Noitoen
    replied
    A short in a cable at night and a 160A MCCB (Middle left) that didn't do it's job last week
    You may only view thumbnails in this gallery. This gallery has 1 photos.

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  • Arcane
    replied
    Back in the early 70's I worked for a period at the Port Alice cellulose mill in the north end of Vancouver Island. I was in what was called the small wood plant that cut up the smaller logs (2' and under in diameter) into chips to process into cellulose and the larger logs went to the big wood plant that could up to 4' (IIRC) diameter logs or anything that was cut down to that size in the attached saw mill. The two wood chippers were driven by 4160V electric motors, one for each. IIRC the small one was 1500 HP and the big one was 5000 HP. The small one was fed by a chain drive so you could start, stop and reverse the amount you fed into it but the big plant was fed by a 45 o angled downward chute, once a log was in it, there was no stopping it. One day apparently they had both chippers loaded with the maximum size of log in each and the huge current draw cause the main breaker to open but for whatever reason it didn't extinguish the arc and it kept arcing and arcing and arcing until the entire breaker room, at least 10' x 12' (IIRC) or slightly larger was destroyed. They gave some of us a look at it soon after it happened and the best way I can describe it is it looked like a huge fire had burned inside it for a considerable time. Picture a regular house breaker box after it had been in a burning barrel for hours, that's what the whole inside of that breaker room looked like. I can not even begin to imagine what it must have been like in there when the arc first started and immediately afterwards.

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  • rdfeil
    replied
    Originally posted by Richard P Wilson View Post

    What is an EE?
    Electrical Engineer

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  • PStechPaul
    replied
    Electricity Exploder?

    Exciting Experimenter?

    A wide shoe size?

    but usually Electrical Engineer...

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  • Richard P Wilson
    replied
    Originally posted by reggie_obe View Post

    He's an EE, I wouldn't have an issue. Obviously his neighbors don't either.
    What is an EE?

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  • RB211
    replied
    He was stepping up the voltage, wasn’t fully charging his capacitor bank. If he had, he would of blown it up first try.

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  • J Tiers
    replied
    Originally posted by Paul Alciatore View Post
    What surprised me was when he opened it and found an array of smaller Amperage fuse links inside. If you are not careful, you can get a chain reaction with that with the one that passes the most current going first and then the next and the next and the next, etc. They must go to some process to match those individual fuse links. A real QC process.
    I'd think that it is almost a guarantee that will happen. But presumably at those sorts of currents, the process does not take too long. After a few go, the process should start to accelerate rapidly.

    It's likely that there is no practical alternative to that construction. A big chunk of material might not react well, and then there is the question of where the material goes when the fuse elements melt.

    I did not catch the voltage rating of that fuse. I'd be surprised if it was as high as his applied voltage seems to have been. The spacing of the plates is not that large, and there are a lot of little bits that must go somewhere in there when the fuse opens, because with the enclosure complete, there is nowhere for the open elements to go, they have to open and stay generally in place.

    The interesting thing was the fact that it took several tries for it to open completely. It appears that while he could produce the CURRENT, he did not have available the ENERGY required to open the fuse. He could produce the peak current, but not for long enough to fully "blow" the fuse.

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  • Paul Alciatore
    replied
    What surprised me was when he opened it and found an array of smaller Amperage fuse links inside. If you are not careful, you can get a chain reaction with that with the one that passes the most current going first and then the next and the next and the next, etc. They must go to some process to match those individual fuse links. A real QC process.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Arcane View Post

    Just because he's an EE doesn't mean he has a clue about safety. **** happens and you have to take that into account when you are dealing with the energy he is. You simply can't work on the premise of "Nothing can go wrong."
    True enough. That goes for PEs as well as just degreed engineers. Some of the worst offenders I have seen are PEs.

    When I set up a test of some 750VDC equipment, I would make sure that the meters and wires etc as well as the stuff under test were fastened down sufficiently there would be the least chance of a "woopsie" but we could still easily do the test that was needed. The kill switch was always accessible, and clear of the other stuff, so you would not get a bad suntan while trying to shut the thing off..

    The PE would set stuff on the test table, hook it up with test leads and whatever he had to hand, then go poking around with a hand held meter and small clips. on live 750VDC equipment. The setup usually looked like a rat's nest. He got away with it all but two times, one time did not cause any real damage, just a very surprising loud bang when something conductive got into the wrong place. The other time, he didn't think ahead, and had used the smallest size Anderson connector. When there was a fault, he pulled that connector, but dropped it in a hurry when it began arcing across the contacts. We had to shut that off.

    Oh, I forgot the other time, when he actually was at lunch, not there, and his long term test setup fried a transformer while working at about 60kW. I had not been involved with that one, and did not know where the (not marked) kill switch was, so I sent the tech who built it to hit the switch (which turned out to be on the wall 3 feet BEHIND the setup... really?), while I went around the other way with a fire extinguisher to put out the transformer which was at the far end (but still only 4 feet from the kill switch, which it blocked from that side).

    You gotta watch out for the PEs, as well as any other engineers who are not as hands-on. You never know what kinda crap they will get into.


    Last edited by J Tiers; 09-20-2021, 12:29 AM.

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  • PStechPaul
    replied

    Most of my career was designing and servicing test equipment for protective devices such as circuit breakers and reclosers. We made test sets rated at up to 10,000 amps continuous and pulses up to 100,000. Mostly AC, some DC. However, the output voltage was typically less than 20 volts. Results were not nearly as dramatic, however.

    I have a 3000 amp fuse removed from a huge DC test set we serviced in Atlanta.

    Click image for larger version  Name:	3000A_Fuse_3570.jpg Views:	2 Size:	104.0 KB ID:	1962175

    It had eighteen 2600 amp SCRs to provide an adjustable DC output current up to about 20,000 amps, for testing large circuit breakers up to 4000 amp frame size as used in nuclear power plants.

    Click image for larger version  Name:	2600A_SCR_3571.jpg Views:	2 Size:	109.8 KB ID:	1962176

    Click image for larger version  Name:	GE_Atlanta_0149.jpg Views:	2 Size:	146.6 KB ID:	1962177
    Click image for larger version  Name:	GE_Atlanta_0154.jpg Views:	2 Size:	175.4 KB ID:	1962178
    Click image for larger version  Name:	GE_Atlanta_0159.jpg Views:	2 Size:	174.2 KB ID:	1962179
    Last edited by PStechPaul; 09-19-2021, 11:05 PM.

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  • Cheap Jon
    replied
    Back in 1978 I worked in a experimental steel extrusion plant. A induction furnace was used to heat up 9"x39" steel rounds. Each of the 6 lines had 3 coils, number 1 drew 1500 amps number 2 drew 900 amps, and 3 drew 600 amps. The whole thing sat on a cement block in closer that contained 2, 12000 volt to 480 volt transformers,9 reactor control cabinets, and 9 large capacitor cabinets that were full of caps like were in the video. The electricians had special jumper cables that they used to short them out, sounded like a gun range. The coils where connected with water cooled cables that sprung leaks that ran water into the cabinets, causing loud banging, shaking. One day there was a blue ball of fire the size of a basket ball just hovering over the coils.
    On my last job we had a rat get in the switch gear and short across the bus blowing 2 2500amp fuses, surprisingly the rat was a little bloody but intact, the bus was not damaged, 4 new fuse that I think cost $2500.

    Jon
    SW Mi

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