Re: High Voltage but Low Current fuses...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

what about a "fusible link" type scheme.. a short piece of AWG 30 wire or
smaller.. There's an equation for fusing current/time on my webpage
  and, yes, embedding the wire in sand will help a lot (or, if you can
tolerate the inductance, wrapping it around a form that can absorb some
heat/quench the arc.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, July 13, 2003 8:18 PM
Subject: High Voltage but Low Current fuses...


 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi All,
 >
 > My differential probes and cap life test seem to require fuses with the
 > following characteristics:
 >
 > 1.  ~30000 V withstand and break.
 >
 > 2.  About 250mA of fuse current, but NOT at all critical.  The current is
 > either 100 mA (normal) or 500 amps (Yipps!!  turn it
 > off!!)  ;-))  Basically a far "much less than 1 amp" but very high voltage
 > fuse...
 >
 > 3.  A few amps of break current.  If say a pulse cap were to discharge
 > though it, the current might be very high briefly, but it would quickly
 > drain off.  Hi instantaneous currents are ok, but the sustained current
the
 > fuse would need to stop are low like a few amps (MOT).
 >
 > MOVs can take a hit, but then the current needs to "stop" before they burn
 > up...
 >
 > 4.  Cheap ;-))  Maybe something a person could just make themselves or
find
 > at some easy to by from source (web sales and "individual" purchasers ok).
 >
 > I was thinking of winding a long thin wire on a "star" form in a long
 > spiral to provide many break points and a long arc path would work.  I
hear
 > that putting it in baking soda or sand helps...  I see people drawing
those
 > big six inch arcs of a MOT which is "bad" for a fuse that has to stop such
 > arcs...  A fuse on the MOT would stop that 20 amp draw on the primary...
 >
 > Any ideas are welcome.  Both of my little projects seem to need darn good
 > high voltage fuses...  The fuses themselves might become the third project
 > ;-))
 >
 > Cheers,
 >
 > Terry
 >
 >
 >