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Re: Three phase rectifiers

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi Greg, Finn, All!

Date: 04 February 2001 04:15
Subject: Re: Three phase rectifiers

>Original poster: "Greg Leyh by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <lod-at-pacbell-dot-net>
>Original poster: "Finn Hammer by way of Terry Fritz
>> Would you please explain how to determine a proper sized
charging choke
>> in a system, where transformer voltage and capacitor size
is already
>> given, so that it results in the desired doubling of the
voltage across
>> the cap/vs the input voltage, while keeping the current
from the
>> transformer to the gap during ringdown low enough  to
allow quenching of
>> the gap without making a rapid recharge of the cap


>The charging action
>of the reactor has no effect on gap quenching, since the
reactor current
>is zero when the gap fires, and is held at zero by its
massive inertia.

So this is what I was doing when I stuck a couple of
resonant chokes into the two hot lines of my 500VA NST
system ;-)  I didn't consider it from that point of view, I
was simply trying to improve the efficiency of the thing
(which it probably does) and was a bit taken aback when I
could pull inch+ long sparks off the chokes (it's a 10/50
NST) - thanks for this info!  Do you (or anyone else) know
if the use of chokes helps to regulate the firing of static
gaps, as I would intuitively think it does if the charging
is regulated by a resonance phenomenon?

But surely the fact that the inductors hold the current at
zero when the gap fires tends to help prevent power arcing
from the psu?  I could have sworn that the output of my
small coil got "cleaner" when I used the chokes, even given
I have the magnetic limiting of the NST.  By "cleaner" I
mean that the note emitted by the arcs was less raspy (less
low frequency content) and more like a high-frequency hiss.
Break rate was around 6000 per second and I assume that the
action of the shunts can't quite follow this as they would
at 50c/s, NSTs not being intended for hi-fi reproduction :-)