I forgot. There is in fact a metal connection, sort of, that fuses without
explosion, soot and splashing metal drops. When too high current passes, it
breaks, nicely and with no dramatic aftermats. You are all a foot or two
from it every day, most of you half an hour in the morning and half an hour
or so in the evening. What do i think of?
No, no, no.. Dave Hillman....not you again. Let others guess first. Yes, I
know you are a MENSA member...
Inge
--------------------------------------------------
From: "Inge" <[log in to unmask]>
Sent: den 20 May 2010 20:37
To: "Glidden, Kevin" <[log in to unmask]>; <[log in to unmask]>
Subject: Re: [TN] Visual clues of over-current for leads
> Kevin.
>
> that was an odd question my friend. What benefit do you have of a
> catastroph failure photo? Sure, I have all kinds of photo material, but
> to scan hundreds of reports to find a particular photo takes time. Instead
> I go directly to your question. It depends (Doug TM) on the kind of
> circuitry you have. Resistive? Inductive? Current limitation? Lead
> material? Heat paths? Lead cross section area? Lead length? etc
>
> Let's compare with a gold bond 1 mil wire. Despite it's thinness, it's
> capable of taking 6 amperes DC for some milliseconds. Then imagine a
> component lead!! Maybe a hundred amperes instantly. Overcurrent can
> appear as a) a inrush current high enough to rise the resistive current so
> fast that you melt the lead within milliseconds. The temperature reaches
> thousands degrees and the hottest part of the lead vaporises. Typically,
> it acts like an explosion. Melt metal spreads around, oxides and soot
> covers the surroundings and there is a smell of burnt material. The
> voltage drops, some major fuse breaks and nothing more happens. This is
> the most positive scenario. What is far more dangerous is if the voltage
> does not drop (it can increase instead, inductive load) but continues to
> feed, arcing can start and put fire to surrounding components. So, my
> answer is: if the overcurrent disintegrates a lead, there will NOT be left
> a smooth and clean metal, because that is against all physical laws. With
> one exception. Theoretically, if the short circuit current is 'unlimited'
> and dt/T is 'zero' , the lead may break by electromechanical forces rather
> than by thermal causes. The inventors have tried for may years to design
> fuses that behave like that. If your leg broke by overcurrent and is
> still smooth and clean, hurry , take patent .
>
> My two amperes
>
> Inge
>
>
>
> --------------------------------------------------
> From: "Glidden, Kevin" <[log in to unmask]>
> Sent: den 20 May 2010 19:53
> To: <[log in to unmask]>
> Subject: [TN] Visual clues of over-current for leads
>
>> Hello,
>>
>> Can anyone describe or provide photos of what one might expect a lead
>> that has been subjected to such a high current that it damaged (burned?
>> disintegrated?) the lead?
>>
>> Would you expect to see charring all the time? Is it possible to see
>> smooth, clean surfaces with just a section of the lead missing?
>>
>>
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