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Most spectacular failures

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LAN_403

HV Enthusiast

Mon Feb 20 2006, 05:50PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Yes, that was a Fairchild 40N60 type IGBT during a ground arc. Probably about 700A peak current before it cross-conducted and exploded.

Marko

Mon Feb 20 2006, 06:54PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Lool small coil but looked very good.. until went bang
Obivously mosfet burst into sparkles and flame, seems like explosion damaged the secondary

Is that coil alive today??

Interesting thread in the end

Tesladownunder

Mon Feb 20 2006, 07:08PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Some sparks between my pulse caps in the aftermath of an exploding aluminium foil shot. They are the vertical ones on the right.
I looked for any problems with the busbars and found none. Something was wrong. The cap cases were all joined with busbar.

In fact it was not a fault but just a reflection of the voltage across the busbar during a (perhaps) 100kA discharge. The inductance of the section of bus bar which is L shaped suggests that it could have had 600V across the cap cases with 1000's of amps available. Easily enough to give some decent sparks.

Apart from that I have never had anything blow up, be over volted, overheated ......
(Liar, liar, pants on fire...)

Peter

1140462493 10 FT1665 Cancrusher4vidstill3kj1

Marko

Mon Feb 20 2006, 07:15PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

You never blaw even bc547 in your life??

Just horror stories are enough no pics are needed

I had mosfets blow in my face but eyes were fast enough, also had some and some almost exploding capacitors (once one big was overvolted by SMPS output without regulation, it started bulbing and continued even when I turned power off, I ran away but it didnt explode... :)

Once as a small kid I ran cap in reverse to see what will happen, and blew it across garage (poor man's exploding stuff)...

Nik

Mon Feb 20 2006, 08:37PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I had a small cap on a motherboard explode in the maner of a large orange flash followed by lots of blue smoke. The smoke then turned into "threads" in the air which then fell onto the case where it became a perminant smudge.

I blame compaq

Simon

Mon Feb 20 2006, 11:36PM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

Sounds like a tantalum.

I love the pictures, Steve and EVR! Come on, Steve! An image like that demands more explanation than "Whee".

Spectacular failures? Hmm, I've had the usual pops and magic smoke but let's see...

Some years ago in way more ignorant days I tried to blow up a fat 'lytic by plugging it into the mains. (NOT recommended. I was a moron for doing this.) I screwed it inside a jam jar, wired it up and turned on the power. The circuit breakers tripped.

Hmm, I thought, I need a current limiting resistor. I scrounged around and found a "big" low-value resistor. I wired it up.

I wasn't so bad a n00b and I was some distance away, behind cover and facing the opposite direction when I turned on the power. This time there was a great flash of light.

I worked out later, when a little wiser, that I'd put ~2500W through a 1W resistor. Part of the resistor had promptly exploded and the plasma had touched the metal jam jar lid, which was on the ground. The resulting arc would have been what had made the flash.

Time to be grateful for the speed of RCDs.

I'll repeat: I was a moron at this point.

Philcogrump

Tue Feb 21 2006, 01:33AM

Registered Member #212 Joined: Sun Feb 19 2006, 05:42PM
Location: Texas
Posts: 20

I generally would try to avoid failures as much as possible. The only spectacular failure I experienced was on purpose, and I did this in my second year of electronics class at high school...

I took one of these old computer PSUs with the switching power supply system. I took a BIG old AC flyback from a mid-70s TV and hooked the lowest resistance winding of the flyback to the primary of the ferrite-core transformer on the switching power supply. I turned it on (no variac) and the flyback worked nicely giving out about 1-inch AC discharges in the air so I put the whole thing on a board. My teacher took it out and demonstrated it to the class and held the board with the circuit in his hand while it was running for about 15-20 seconds and I was a bit afraid the switching PSU wouldn't like it for such a long time. I was right, the 0.6A fuse blew violently with a bright blue-white flash then the thing died and that was just before the school bell rang.

The next time I came to class, I investigated to see what happened and saw that the switching power FETs were burnt (not blown... yet). I told my teacher what the problem was and it was "long gone." I took a steel stand-off post and put it in place of the fuse and requested permission from the teacher to plug it in and blow up the parts. He was like "yeah, okay, whatever." I switched it on, immediately the FETs exploded with white/orange flashes then after that for about 4 seconds there was a red flare coming out of them with a FIZZZZZZZ noise which caught attention of the teacher and the class next door.

Avalanche

Tue Feb 21 2006, 10:02AM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

Firkragg wrote ...

Lool small coil but looked very good.. until went bang
Obivously mosfet burst into sparkles and flame, seems like explosion damaged the secondary

Is that coil alive today??

Interesting thread in the end

I haven't got around to replacing the MOSFETS, but I assume it would work again if I did. The strange thing is that you can't really see any damage on the coil anywhere after that video!

I should get that coil running again, I built it in 2 days and blew it up on the 3rd day. Hasn't run since.

Steve Conner

Tue Feb 21 2006, 10:39AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

OK, I guess I should explain a bit more than "Whee"... That was the remains of the H-bridge from my first DRSSTC. It worked great for about 1 minute, putting out 3ft long sparks, and then blew up with a white flash and huge bang. I found pieces of the IGBTs lying about 10ft away from the explosion site :-@

I think the reason it blew was that the primary current was extremely high. I used the primary and secondary coils from my old spark-gap Tesla coil, and they weren't too well suited to a DRSSTC.

1140518359 30 FT1665 Img 0750 Drsstc H Sm

Marko

Tue Feb 21 2006, 06:11PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I vote for avalanche's film, also blew mains fuse and set dark in room, but still hot fragments are visible in the air

I also 'knew' when something may or is going to explode, always expected that and hided propertly.

Once I tested transformer that seemed to have shorted (too low resistance) primary and I hooked it to mains trough a fuse.
Problem is that I had only 20A fuse at hand so I hided well and hookd it, fuse pulverized into smal fragments in a blue flash.
Bad transformer obivously.
One time I had nasty mercury arc lamp explosion.

Except mosfets (only two blown are visible on the picture, others trashed..) shooting my face once I turned a tantalum capacitor backwards.
It exploded immediately at poweron in my face, I felt fragments of it but on closed eyes (they have been faster this time)

Im now sad I didnt keep pulverized remains of transistors, I had a nice graveyard...

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