Re: Three phase rectifiers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "brian by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ka1bbg1-at-mcttelecom-dot-com>

hi, have a look at www.rectron-dot-com 1n5408 is good but i like fr307 much
better and about same price. cul brian
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, February 01, 2001 9:05 PM
Subject: Re: Three phase rectifiers


> Original poster: "Greg Leyh by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<lod-at-pacbell-dot-net>
>
> >     I have worked out the wiring for my 3 phase rectifier design. I am
> > going for a design voltage of 12kv at 1 amp. I would like some feedback
> > on the best way to go about choosing the diodes. I am going for the 12
> > pulse recifier design shown here (scroll down the page)
> > http://ham.te.hik.se/homepage/sm5bsz/supply.htm
>
>
> Yes, it's a good idea to get them all from one batch.  Each
> diode should have an RC snubber ckt around it, as well.  I'd
> splurge for the 3A diodes though, since there will be a lot
> of current spikes from parasitic effects at those voltages,
> and from the unballasted filter cap shown, at startup.
>
> A 12-pulse system would be very nice, indeed.  A 6-pulse set
> produces too much ripple, I assume?  I'm totally envious of
> the /standard/ 3-phase mains, that European households enjoy!
>
> One item that might be problematic in the circuit is the
> wye-connected primary set.  Normally, 3ph power xfmrs are
> connected delta-delta or delta-wye, since wye primaries have
> a tendency to launch heavy 3rd harmonics onto the neutral...
> especially when there is an un-ballasted cap right after
> the diodes.  There is also the possibility in a wye-primary
> of intermittent core saturation events, unless the neutral
> has a /very/ low impedance.  This will be evidenced by the
> main breaker tripping randomly when power is applied, and
> substantial overvoltage spikes at the DC output.
>
> You mentioned that there are two types of xfmrs in the
> circuit.  I assume that means they have different turns
> ratios... one for the delta, and one for the wye?
> ---
>
>
> -GL
> www.lod-dot-org
>
>
>
>