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Re: DC Supplies & Protection
> Original Poster: Mark Finnis <mefinnis-at-medicine.adelaide.edu.au>
>
> Further to recent posts, I am researching a 3-phase full-wave DC supply
> using NSTs and an async-RSG.
>
> Leaving the rectification bit for a moment, what about protection ?
>
> Have followed Malcolm/Terry's work and use only an RC filter for my current
> NST supply and this appears to work very well (read my 2 NSTs are alive
> and well and the safety gap virtually never fires).
>
> Now DC is going to be a little different. We wont have to worry about
> harmonics induced from the primary resonant circuit ....... or will we ???
>
> Will chokes have a real place here (I strongly suspect to protect the
> semi-conductors of the bridge) ??
A choke in series with the rectifiers could be very bad,
especially if the diodes are slow recovery types. (The
reverse recovery current builds a field in the inductor,
and upon the recovery snap, so goes the diode!
Here is when it's _very_ useful to do some PSPICE modeling.
You must know what kind of event you're protecting against!
I could imagine being better off with an RC filter (no Q)
or even no filter at all.
--
-GL
www.lod-dot-org