Re: Diode Strings

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

Original poster: "Richard W." <potluckutk-at-comcast-dot-net> 


----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, August 22, 2004 5:26 PM
Subject: Re: Diode Strings


 > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
 >

 >
 > It also pays to consider what happens if the output gets shorted
 > momentarily.  I've killed a number of bridge rectifiers in pulse discharge
 > applications because I didn't realize that if the output voltage reverses
 > (as in the ringing from a sudden discharge of the filter), the diodes die
a
 > quick death.
 >
 > There are other scenarios that one should consider, too.  What if one or
 > both the input to the rectifier goes open or shorted?  This might never
 > occur in your design, then you wouldn't need to consider it, but you
should
 > look at all the "credible faults", at least casually.
 >

Good point and I agree completely.
To at least attempt to minimize that situation then add more diodes?

If diodes failed open then some of the damage wouldn't happen but they
usually fail shorted.
There may not be a "bulletproof" method of rectification but I'd gladly
incorparate fail-safe methods/designs if there are any that I'm not aware of
and therein lies the motivation for asking about this subject. So far I've
been able to build components with a very high confidence that they won't
fail under the conditions they were designed for, using over-engineering
where possible and going a few steps ahead to help minimize foreseeable
failures.

I've seen a "movie" of a guy whose diode string failed and the resulting
explosion is something I'd like to prevent. I understand there are no
guarantees when it comes to HV and component failure but I figure it's best
to ask for as much input as possible instead of learning by hindsight.

 > "look at all the "credible faults", at least casually."
You bet. And possibly more than just casually. :)

I really appreciate the replies thus far and the time given from those that
have responded.
Experience, wisdom and knowledge from others is a resource far too important
to ignore.

Rick W
Salt Lake City