--- In
ham_amplifiers@yahoogroups.com, R L Measures wrote:
>
>
> On Oct 30, 2006, at 1:08 AM, Frank Goenninger wrote:
>
> > Hi all:
> >
> > I am about to finish my HV power
supply. One thing missing still
is
> > an appropriate HV fuse to be put between C bank and glitch R.
While
> > closely examining the pictures in the photos section of this
group I
> > couldn't find any European manufacturer or distributor of HV
fuses.
> >
> > I found SIBA () - but they do provide fuses for
> > even "bigger" applications.
.. I'd need something suitable for
the 3,5
> > kV / 3 A coming out of my 300 F C bank...
> >
> > Any suggestions? Thx for feedback!
>
>RICH SEZ.... Hello, Frank == A HV fuse in the secondary does not
protect the HV- transformer any better than a circuit breaker in
the primary. cheerz
### What about protecting everything else ???? Short the B+ to
the chassis/ anywhere... and when comparing a fast HV fuse vs the
fastest magnetic hydraulic breaker
in the 240 V pri.... the
difference is blatantly obvious. Been there.. done that. The only
thing faster than the fastest breaker is... "rectifier and
semiconductor" pri fuses... available up to sevral hundred amps.
These fuses can be used to supplement a slow breaker.... OR can be
used in cases where the breaker rating is way too high to start
with. [eg: multiple sec HV taps on a plate xfmr... where u want
to run say a single 3CX-800A7 on 6m one day... and 15 kw out the
next day, with a different amp of course.]
### Primary AC protection is way too slow imo. Since my xfmr has
loads of sec taps... I use it at different voltages... so a 100 A
breaker in the primary is too big for some applications. Another
Fix is to use a pair of 50 A double pole breaker's...
. and
parallel each pair. By removing the tie-bar between em.... for
50 A operation... one pole on each breaker is shut off.
### If u are gonna
parallel a 2 x pole 50A breaker, so it
handles 100 A... you have to do it right.... enter on one
corner...and exit diagonally on the output. Then the current
will split 50-50 on the poles.
### This scheme also works on 3 pole breaker's. [which use 2 x
tie bars per breaker] You can parallel all 3 x poles..... and by
removing the 2 x tie bars on each breaker ...... you can have a
50-100-150 A choice. 2 x such assys are always required.... one
per hot leg on a NA single phase, 240 v circuit.
## Bottom line is.... when a HV fuse open up... nothing happens..
no big deal. They are extremely fast under fault conditions..
.
like <2 msecs.
Later... Jim VE7RF
> >
> > 73 Frank DG1SBG
> > ...
> >
>
> R L Measures, AG6K, 805.386.3734
>
r@..., , rlm@...,
www.somis.org
>
