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 Post subject: Can you have an Arc Blast without having an Arc Flash
PostPosted: Thu May 05, 2011 3:23 pm 
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Joined: Fri Aug 21, 2009 10:20 am
Posts: 6
An issue has come up where a fellow employee used to be a submariner and he saw what he calls an Arc Blast caused by dropping a wrench across a 3 volt cell on their submarine. His point is that if you have enough current no matter the voltage that it will vaporize a wrench and result in an Arc Blast.

My contention is that if you do this, it will melt the wrench but not develop an arc blast, just a lot of molten metal. I would think that if a wrench were to expand by 40,000 (or I have seen by 67,000) times that it would have consumed the majority of the interior of a fairly large submarine.

What say you?

I have also been looking for references on voltage and current levels that are required for an Arc Blast. Does anyone have such a reference?


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PostPosted: Fri May 06, 2011 5:53 am 
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Joined: Mon Jun 02, 2008 11:58 am
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Location: Charlotte, NC
Bubbleheads tend to exagerate :)

Keep in mind a cell on a submarine battery system is not your typical battery cell, about the size of a fridge, and can release around 1MW (As I recall) of enegry if shorted.

IEEE 1584 mentions an arc will not be slef sustaining at <240V if fed from a single transformer <125kVA. That is about it for a reference. There has been little research published on arc blasts, but it is in the works.

Our host here may have some insight to the current research.


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PostPosted: Mon May 09, 2011 9:53 am 
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Interesting video on very large Battery Short Circuit

Found an interesting video where they are shorting a bank of batteries pulled out of the nuclear submarine that is 42 volts and 25,000 AmpHrs. He mentions there is around 3000 to 5000 amps flowing during these short circuits. There is considerable arcing going on but nothing I would describe as an Arc Flash or even an Arc Blast. Maybe an Arc Pop (new term... :o ). It's audible but isn't violent like videos I've seen with real Arc Blasts.

The Leidenfrost Affect is kind of interesting. Here is the link: http://video.google.com/videoplay?docid=7885018544864978920#


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