[Amps] HV Fuses

[Roger]

Alex Eban wrote:
> Actually the filler in HV fuses is silica, not sand.
> The main purpose is to snuff off the arc that can generate a plasma short.
> It is found in heating elements in electrical boilers and kettles.
> If you dismantle an old HV fuse carefully, you can install a new wire and
> then pour back in the silica. It'll be as good as new.
>   
There's a hole in each end cap so you solder the one end, put the cap in 
place, hold the wire tight, pour in the silica, slip the cap over the 
other end of the wire and over the tube, Pull the wire tight and 
solder.  It's a fairly easy operation.  I used to have a whole bunch of 
them used in the high voltage line to penning tubes.

73

Roger (K8RI)
> Alex	4Z5KS
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Carl
> Sent: Wednesday, February 17, 2010 3:24 AM
> To: K1SG at aol.com; amps at contesting.com
> Subject: Re: [Amps] HV Fuses
>
> QRO requires some sacrifice Steve, its called money(-;
>
> The bad news with your idea is that at that voltage you have a better than
> equal chance to create a nice plasma arc with attendant serious damage. If
> it was so easy HV fuses wouldnt be used by all commercial products outside
> of the ham community.
>
> HV fuses show up at hamfests and fleabay for a few bucks.
>
> The creative should be able to duplicate a real HV fuse.
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: <K1SG at aol.com>
> To: <amps at contesting.com>
> Sent: Tuesday, February 16, 2010 6:59 PM
> Subject: [Amps] HV Fuses
>
>
>   
>> In recent threads, there have been a number of comments about high voltage
>> fuses.
>> Carl mentioned sand-filled fuses, something I hadn't heard of.
>> I checked the Mouser catalog for HV fuses, and was stricken with
>> sticker-shock...$38 for a fuse?
>> OK, we re-think this one...
>> I know that an old but workable approach is  to use  a thin piece of wire
>> as a fuse...mount it between a couple of  standoff insulators, and it 
>> should
>> function fine, and if current is  substantially too high, the fuse wire
>> blows. How do you figure the appropriate  size wire to use? And then, how 
>> do you
>> go about ordering 6" of #30 wire, or  whatever it is? If you need more
>> current capacity, to use the above example, can  I put two strands of #30 
>> wire
>> in parallel, and expect them to function as a  reliable fuse?  I'm always
>> worried about kinking the wire, or if it's  enameled, sanding off more 
>> than
>> just the insulation.
>> The plan is to fuse the HV output of a 5KV 2A supply to a 3X3, which of
>> course will only be used at the legal limit or into a dummy load.
>>
>> Steve  Gilbert
>> K1SG
>> K1SG at AOL.com
>> 508-435-9133
>> FN42fe
>>
>>
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>>     
>
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