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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

> 3-phase is cool, but also obligating, since noone should ever draw more
> than, say, 35 amps from one phase only, since this will skew the grid.
> I think the 3-phase rectified supply would be more used, if the function
> of the charging choke was better understood.
> 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 impossible.

Basically, you start with determining the max break rate desired.  An

Max desired break rate = 400 BPS
Cpri = 0.3uF

The resonant charger frequency should be 200Hz, since the capacitor 
will charge in 1/2 cycle of the resonant charger frequency.  You would
then select a value for the charging reactor that will resonate with
the Cpri at 200Hz.

Lchg = 2.11H

Note that this value is completely independent of Vpri, line frequency,
or any variables other than the maxBPS and Cpri.  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.