Date: Sat, 05 Apr 2014 08:41:38 -0700
From: Bill Turner <dezrat1242@wildblue.net>
To: amps@contesting.com
Subject: Re: [Amps] HF2500 Power Supply Caps
On 4/5/2014 8:06 AM, Carl wrote:
> but more C doesnt buy anything useful.
REPLY:
More C can actually be harmful. In case of an arc, more C just dumps
more energy into the arc with potentially more damage.
73, Bill W6WRT
## With a 50 ohm glitch Resistor installed, the peak fault current remains the
same, regardless
of C used. However, the 50 ohm glitch + total C will form a RC time
constant, whose duration
will be longer when more C is used. With 2500 vdc + a 50 ohm glitch
Resistor used, peak fault
current is 50 Amps..... which will easily blow open a 1-2 Amp rated HV
fuse...and under 2 msecs.
## The 50 ohm glitch resistor LIMITS the peak fault current. The HV fuse,
just prior, and in series with the
50 ohm glitch resistor, INTERRUPTS the peak fault current. You can cro-bar
the supply all day long if you want.
All that happens is the HV fuse blows open.
## use whatever size cap you want. The 440-600 uf types work just fine.
The bigger the total C used, the better the
dynamic regulation of the supply. The ripple is also lower, and in
proportion to C used. A 600 uf cap will have one third the
ripple of a 200 uf cap..and way better dynamic regulation on ssb and cw. Your
load line is not all over the map.
Now this all works with the proviso that a 50 ohm glitch R and HV fuse is
used.
## As far as regulation goes, you require a plate xfmr that doesnt sag to begin
with....and big enough ga wire from HV supply
back to main 200A panel. You also require large enough rated relays and
contactors. Any Z between main panel and plate xfmr
will create V drops..which is bad news with any high C filter.
Jim VE7RF
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