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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Jonathan Johnson on October 28, 2014, 03:16:46 pm

Title: "The transformer exploded!"
Post by: Jonathan Johnson on October 28, 2014, 03:16:46 pm
We've had some stormy weather here in the Pacific Northwest lately, and with stormy weather it seems I hear plenty of reports from people who claim "the transformer exploded!"

I don't think so. I've seen transformers that are overloaded; they usually fail by boiling over. Once enough coolant is lost, the insulation on the winding fails, shorts out, and causes the fuse supplying the transformer to blow. When that fuse opens, it does so with a loud bang and a flash of light.

(I have seen transformer fires too, but only in a substation. A lot of smoke and fire was involved, as well as loud bangs that were probably circuit protectors opening under load. I've never actually seen where a transformer has literally exploded; I think there would be so much collateral damage it would make the news with pictures and everything.)

I believe that when someone says "the transformer exploded!" what they have really observed is the fuse opening. But in reality, the transformer has nothing to do with it; severe weather is unlikely to cause a failure of a transformer. More likely, a tree has come in contact with a primary power line, or the wind has caused the wires of the different phases to come in contact with each other, creating a short circuit that results in the opening of the fuse supplying that line, which it does with a loud bang and a flash of light.

Just last Saturday, the fuse for one of the three phases on the pole at the end of my driveway -- which supplies power to my neighbors up the road -- opened with a bang. There's no transformer on that pole. I didn't see it happen but I sure heard it, and a visual inspection confirmed that the fuse had indeed opened.
Title: Re: "The transformer exploded!"
Post by: Mike Sokol on October 28, 2014, 03:53:48 pm
We've had some stormy weather here in the Pacific Northwest lately, and with stormy weather it seems I hear plenty of reports from people who claim "the transformer exploded!"

I'll bet if we tried really hard we could make one explode.  ;)
Title: Re: "The transformer exploded!"
Post by: frank kayser on October 28, 2014, 04:10:17 pm
I'll be if we tried really hard we could make one explode.  ;)
Yeah, Mike, I bet we could. 


Jonathan,
You invoked a d'oh! moment for me... Of course, a fuse like this would indeed fail as you said - NOT the pole transformer.  Should have known that.  Thanks.  And a transformer would go up in a much larger conflagration than a harmless fuse opening flash and bang.  Should have known that, too.
frank
Title: Re: "The transformer exploded!"
Post by: Tom Bourke on October 28, 2014, 04:11:09 pm
I'll be if we tried really hard we could make one explode.  ;)
1.21 jiggy watts! (mix up of Back to the Future and EDM)
Title: Re: "The transformer exploded!"
Post by: John Roberts {JR} on October 28, 2014, 04:17:12 pm
Yes when the fuse on the transformers open it makes a loud report almost like a gun shot.  Common when wind blows a branch onto the high voltage line or a dumb-ass squirrel climbs too close to the sun.

JR
Title: Re: "The transformer exploded!"
Post by: Mike Sokol on October 28, 2014, 04:27:51 pm
Yes when the fuse on the transformers open it makes a loud report almost like a gun shot.  Common when wind blows a branch onto the high voltage line or a dumb-ass squirrel climbs too close to the sun.

JR

I was driving right beside a transformer a few months ago when we had near-tornado winds. Must have taken a tree or branch into the lines which blew the fuse. It was a really pretty green flash (copper?) and a big bang that sounded like a shotgun blast. Very impressive.
Title: Re: "The transformer exploded!"
Post by: Jonathan Johnson on October 28, 2014, 07:38:54 pm
Common when wind blows a branch onto the high voltage line or a dumb-ass squirrel climbs too close to the sun.

However, when a dumb-ass metal thief enters a substation with wire cutters, he often ends up being the fuse.
Title: Re: "The transformer exploded!"
Post by: Tim McCulloch on October 28, 2014, 09:34:44 pm
However, when a dumb-ass metal thief enters a substation with wire cutters, he often ends up being the fuse.

I would accept the inconvenience of power loss if all the copper thieves would hold hands while cutting live substation lines....

My contempt for what is mostly a meth-addiction crime (in our part of the country, anyway) is very high.
Title: Re: "The transformer exploded!"
Post by: Ray Aberle on October 28, 2014, 09:41:06 pm
cue..... the photos..... lol.

Nah, we're all adults and have seen them. For the love of god, please don't post pictures of burned shoes or whatever.
Title: Re: "The transformer exploded!"
Post by: frank kayser on October 28, 2014, 09:44:16 pm
However, when a dumb-ass metal thief enters a substation with wire cutters, he often ends up being the fuse.
At least they found a purpose in life?
Title: Re: "The transformer exploded!"
Post by: TJ (Tom) Cornish on October 28, 2014, 09:47:41 pm
cue..... the photos..... lol.

Nah, we're all adults and have seen them. For the love of god, please don't post pictures of burned shoes or whatever.
Indeed those photos and videos exist.  IMO, YouTube is much scarier than most horror movies, as what we're seeing is actual loss of life.  Friends don't let friends become human frankfurters.
Title: Re: "The transformer exploded!"
Post by: Scott Holtzman on October 28, 2014, 09:55:14 pm
I would accept the inconvenience of power loss if all the copper thieves would hold hands while cutting live substation lines....

My contempt for what is mostly a meth-addiction crime (in our part of the country, anyway) is very high.

We have had three separate instances of people stealing our fiber.  If it wasn't for the money and customer inconvenience it would be funny.  We are a small business and these short fiber runs are our bread and butter.

Would love to see the look on their face when they go to strip the wire and find it full of glass.
Title: Re: "The transformer exploded!"
Post by: Jim Rutherford on October 28, 2014, 10:01:25 pm
Video of a transformer explosion
http://www.youtube.com/watch?v=rHVh0KwG_0k
Title: Re: "The transformer exploded!"
Post by: Cailen Waddell on October 29, 2014, 07:47:13 am

Video of a transformer explosion
http://www.youtube.com/watch?v=rHVh0KwG_0k

That arc doesn't appear to be coming from the pole mounted transformer... 


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Title: Re: "The transformer exploded!"
Post by: Stephen Swaffer on October 29, 2014, 08:33:12 am
That arc doesn't appear to be coming from the pole mounted transformer... 


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Agreed-looks like the cut-out/fuse.  I have learned to just interpret non-electricians terminology and found trying to correct it usually gets you no where.  Any time a light blinks it is a "short" in the wiring.  Really? A short should typically make me reset a breaker before the lights comes on, more likely (and a far more common fault) is a loose connection/bad contacts on switch/socket, etc.

This is a very graphic demo of the power of an arc flash.  Imagine standing in front of a disconnect switch when that happens!  That is an area non electricians often take too casually-overload tripped?  I'll just open the cabinet and reset it-WITH the start circuit energized so the motor starts right up, fuse blown-just pop in another one-don't bother turning anything off. There is  more energy available at the main breaker of your home than in the chamber of most loaded guns-it really should get the same respect.  "They" called this a transformer explosion-it was an explosion-but people cannot imagine a fuse exploding being this dramatic, even though that is reality.

It also demonstrates the type of fault arc flash breakers are made to stop.  I am sure there was appropriate OCP ahead of this fault-but it was an arcing fault not a short or overload, so normal OCP does not detect a problem. 
Title: Re: "The transformer exploded!"
Post by: Robert Piascik on October 29, 2014, 09:06:40 am
I'll bet if we tried really hard we could make one explode.  ;)


Sokol, it's this kind of attitude that makes me happy that you're the moderator here

Title: Re: "The transformer exploded!"
Post by: Mike Sokol on October 29, 2014, 10:39:57 am

Sokol, it's this kind of attitude that makes me happy that you're the moderator here

Thanks.... I aim to please. :D
Title: Re: "The transformer exploded!"
Post by: Jay Barracato on October 29, 2014, 11:29:45 am
I have seen one explode. I happily use the term explode because all that was left of the top of the pole was splinters of wood and scraps of metal scattered over a fifty yard radius.

(I suspect the fuse blew as well but since all that was left was loose ends of wires there wasn't much of a circuit anyways.)

The cause was a direct hit by a single bolt of lightning.

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Title: Re: "The transformer exploded!"
Post by: John Roberts {JR} on October 29, 2014, 11:34:07 am
I have seen one explode. I happily use the term explode because all that was left of the top of the pole was splinters of wood and scraps of metal scattered over a fifty yard radius.

(I suspect the fuse blew as well but since all that was left was loose ends of wires there wasn't much of a circuit anyways.)

The cause was a direct hit by a single bolt of lightning.

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Yup, I can imagine a sealed metal can full of oil, to explosively expand when heated like that. I wonder if the toxic oil is still dangerous after being vaporized?

JR
Title: Re: "The transformer exploded!"
Post by: Mike Sokol on October 29, 2014, 11:41:07 am
I wonder if the toxic oil is still dangerous after being vaporized?

Maybe it creates Zombies...  ???
Title: Re: "The transformer exploded!"
Post by: Nick Enright on October 29, 2014, 12:27:02 pm
I'll bet if we tried really hard we could make one explode.  ;)

http://www.youtube.com/watch?v=AVfu3bSsBh8

After bunches of bad weather late this summer, the annual block party in the Wayne State off campus area was cancelled at 9ish by this.

 Theory: after repairing the local grid sufficiently to get the residents power, the additional draw of a very hot day, 4 stages, tens of thousands of partyiers, overloaded this transformer.

But why didn't it cause the OCPD to pop?
Title: Re: "The transformer exploded!"
Post by: Rob Spence on October 29, 2014, 12:39:52 pm
Maybe it creates Zombies...  ???

Not sure if this is universal but my understanding is that the black painted transformers of yesterday were the ones with PCPs but the grey ones of today have a safer (note, I didn't say safe) cooling fluid.


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Title: Re: "The transformer exploded!"
Post by: g'bye, Dick Rees on October 29, 2014, 01:04:44 pm
Not sure if this is universal but my understanding is that the black painted transformers of yesterday were the ones with PCPs but the grey ones of today have a safer (note, I didn't say safe) cooling fluid.


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The grey one in our alley blew up and the POCO had to remove substantial amounts of contaminated soil...PCB's.

There's still a patch of the oiled gravel alley where the snow melts mysteriously...right under the new pole/transformer.
Title: Re: "The transformer exploded!"
Post by: John Roberts {JR} on October 29, 2014, 01:12:17 pm
I don't know if MSPower was being excessively cautious but when Katrina dropped my pole and (gray) transformer in my yard, leaking some oil, they carted away a bunch of contaminated soil/turf.

My transformer was probably mid 20th century so likely used PCBs.

JR
Title: Re: "The transformer exploded!"
Post by: Dennis Wiggins on October 29, 2014, 02:02:35 pm
This also...

www.youtube.com/watch?v=yX5TIDLvMyw

-Dennis
Title: Re: "The transformer exploded!"
Post by: Tim McCulloch on October 29, 2014, 02:15:38 pm
Not sure if this is universal but my understanding is that the black painted transformers of yesterday were the ones with PCPs but the grey ones of today have a safer (note, I didn't say safe) cooling fluid.


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I think it's PCB -Polychlorinated biphenyl, nasty toxic cancer-inducing stuff.
Title: Re: "The transformer exploded!"
Post by: Jay Barracato on October 29, 2014, 02:29:48 pm
One of my early research projects was using hyperthermophilic  archea to bioremediate PCB's.

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Title: Re: "The transformer exploded!"
Post by: Jonathan Johnson on October 29, 2014, 04:23:25 pm
I think it's PCB -Polychlorinated biphenyl, nasty toxic cancer-inducing stuff.

I think you're right. I doubt transformers would contain phencyclidine (PCP), more commonly known as Angel Dust. I suppose the hallucinogenic effects of PCP could cause someone to think a transformer is exploding inside his head.
Title: Re: "The transformer exploded!"
Post by: John Roberts {JR} on October 29, 2014, 04:27:41 pm
PCB manufacture was banned in 1979 so products older than that (like my transformer) could contain them.

JR
Title: Re: "The transformer exploded!"
Post by: g'bye, Dick Rees on October 29, 2014, 04:33:33 pm
One of my early research projects was using hyperthermophilic  archea to bioremediate PCB's.

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Sounds like fun, guy.
Title: Re: "The transformer exploded!"
Post by: Rob Spence on October 29, 2014, 05:44:19 pm
I think you're right. I doubt transformers would contain phencyclidine (PCP), more commonly known as Angel Dust. I suppose the hallucinogenic effects of PCP could cause someone to think a transformer is exploding inside his head.

Yup, oops, darn spelling correkton.


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Title: Re: "The transformer exploded!"
Post by: Scott Holtzman on October 29, 2014, 05:47:07 pm
Yup, oops, darn spelling correkton.


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You better be careful, while they are stealing the copper they will try and snort the transformer.

I have been in building basements that still have PCB transformers in the vault.  All sorts of signage.

My understanding is it was replaced with simple mineral oil.

Title: Re: "The transformer exploded!"
Post by: Jonathan Johnson on October 29, 2014, 06:55:37 pm
I have been in building basements that still have PCB transformers in the vault.  All sorts of signage.

My understanding is it was replaced with simple mineral oil.

As I understand it, the oil containing PCBs had the advantage of being fire resistant. While mineral oil isn't known to be carcinogenic at incidental levels of exposure, it IS flammable.
Title: Re: "The transformer exploded!"
Post by: Jeff Bankston on November 04, 2014, 06:09:48 am
back in the 80's i was an electrician on a j.c. penny store in jackson missisppi. our company had a 45kva 480/208-120 3 phase transformer out side tied to a 480v service. one of the guys had built a little shed over it to keep the rain out. 2 guys would sit on the little shed and eat their lunch. after lunch we were working and all the power went out. after a few minutes i went outside and there were 2 holes in the front and back covers about 6" in dia iirc. the guts were a tiny mess of molten copper in the bottom. yep that one had copper coils. it blew up , isnt that awful. the foreman went a got another 45kva and no one went near it after that.