Thanks for taking the time to respond,
everyone
No, I'm not designing fuses AT ALL.
My only interest is in the fact that when
Jeff asked about fusing, I realized that the
new "Current Carrying" guideline didn't
address that subject, and I think it should
at least mention it.
I'm hoping if nothing else we can just plop
the chart in there (from the article) but
I would be nervous to do that without
"checking around" with all you experts
first.
but.... as far as I know, the data is valid
and no one has suggested that it needs
to be modified in any way.
unfortunately, we are running out of time,
the "final" meeting is this Friday!!! might
have to wait for the nxt revision...
thanks again,
Jack
.
On Mon, Apr 27, 2009 at 12:35 PM, Martin Spizman <[log in to unmask]>wrote:
> OK, if you really want a response…
>
> A fusible trace on PCB is not nearly as reliable as a fuse, breaker, or
> other purpose built device. The cost is minimal, so I don’t think anyone has
> really seen a need to work out the relationships between trace sizes, solder
> masking, and base materials.
>
> That said I have used them a couple of time as a secondary defense against
> stupid people. I design professional sound equipment and on one occasion I
> did add narrow traces to an audio input board. Sure enough one day a
> less-than-attentive roadie managed to connect main power to the audio line.
> The traces blew and instead of frying the amplifier, the unit was
> repairable. Now this ONLY worked for me because of the huge difference in
> current between the audio and supply lines. I chose my trace widths with an
> eye towards the minimal width that would still provide adequate conductance
> for the audio signal, but I made no calculation for the burn/melt point of
> the traces. Knowing that the line power was orders of magnitude greater I
> didn’t feel that I needed to.
>
> Of course none of this was included in the customer documentation and there
> is no warranty coverage for this kind of misuse.
>
> I’m sure this is almost no help at all, but I wouldn’t want you to think we
> weren’t listening. ;-)
>
>
>
> Martin
>
>
>
> Date: Fri, 24 Apr 2009 15:14:12 -0500
> From: [log in to unmask]
> Subject: Re: [DC] Is Fusing Current Current?
> To: [log in to unmask]
>
> *wow. *
>
> *Not even one reply?*
>
> *Not even one additional reference?*
>
> *Is this a subject no one has to deal with?*
>
>
> *I'm SO disappointed....*
>
> *tsk, tsk, tsk,*
>
>
>
> *Well, I suppose I should just go home.*
>
> *seeya Monday!*
>
>
>
> *Jack*
>
>
>
>
>
> On Wed, Apr 22, 2009 at 10:07 AM, Jack Olson <[log in to unmask]> wrote:
>
> Greetings all you lurkers...
>
>
>
> Hey, I noticed someone over on TechNet was asking about fusing current,
>
> which prompted me to re-read Doug Brooks extremely valuable 1998 article
>
> on the subject
>
> http://www.ultracad.com/articles/fusing.pdf
>
>
>
> I just realized that this topic would be a perfect addition to the new
> IPC-2152
>
> "Standard for Determining Current-Carrying Capacity in Printed Board
> Design",
>
> and as long as I can put something together by May 1st, I can probably
> insert
>
> it before its too late.
>
>
>
> So my question is, does anyone else have any sources for this subject?
>
>
>
> At the time, Doug wrote it purely from theory (no empirical data) but as
> far as
>
> I know, no one has ever disputed the conclusions and the results have
> always
>
> worked.
>
>
>
> Doug, if you are out there, is there anything in your article you would
> edit after
>
> these ten years? Any refinements?
>
>
>
> currently,
>
> Jack
>
>
>
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