Eico

[Brian Carling]

Interesting Don. Looks like though, in most small audio amplifiers
and receivers, transmitters up to say 100W, that if you added a
small fuse or two on the secondary, say for example, a 1 amp
pigtail, it could only help. Surely it wouldn't arc, and if it only
seperated by 1/8" when it blew and arc'd over to the rest of the fuse
material, THAT would soon blow too? No holder needed anyway.

I am sure now that there is a lot more to this than what I had
thought!!

Happy New Year chaps!

On 1 Jan 2001, at 11:12, DMallozzi at aol.com wrote:

> Hi gang
>
> Regarding Brian's comments about why manufacturers did not use HV voltage
> fuses on the secondaries I can venture a few guesses.
>
> First, (and probably the big driver) is the expense of the fuse and the
> holder are much more than the usual 250 V fuse.
>
> The HV fuses are physically much larger and therefore in smaller equipment
> become a mechanical issue.
>
> Third, many applications we are discussing do not draw large secondary
> currents and the high voltage fuses are typically not available in a lot of
> currects below 1 A.
>
> I have had a little experience using fuses at high voltages (up to 50,000
> VDC) and I can tell you that the use requires some thought. Also, there are
> techniques similar to fuses I have seen in use at above 5 KVDC but they are
> not appropriate for consumer applications.
>
> I had the occassion in one job to test some fuses (250 V) at 5 to 10 times
> there ratings in standoff voltage. The results were things like arcs and
> plasmaing that result in the fuse not interrupting a fault. Some of this is
> due to physical size and construction. The remainder is usually a result of
> the way the fuse link deteroriates. In some fuses to stop the arcing/plasma
> scenario the link is surrounded by a material similar to sand (don't have a
> clue what it actually is) that physically fills the path between the ends of
> the broken link.
>
> If anyone has more insight to this I would like to hear it.
>
> 73's and a Happy and Healthy New Year to all
>
> Dom
> N1DM

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