----- Original Message -----
From: "John" <jlockj@earthlink.net>
To: <K1LE@arrl.net>
Sent: Saturday, December 21, 2002 9:18 PM
Subject: 3CX800A's
> Hi Jeff,
>
> re: snip
>
> > Now most ham amplifiers are single phase and the current from the power
> > supply will have
> > zero crossings and extingish the arcs.
>
> snip
>
> Zero crossings...hmm...sounds like not enough filter C ! ;-)
>
> Jeff - K1LE - CT ><>
>
> snip
>
>
> When you have a short circuit, it's tough to have enough C to keep the
> voltage steady!
>
Hi John,
I was being slightly facetious as "zero crossing" is something that is
relied upon to interrupt arcing across the contacts of an AC circuit
breaker. This is why the DC interrupting rating of a given breaker or switch
is much less than the AC rating.
As I see it, the short circuit current should be limited by the glitch R
(along with other R's and Z's in the fault circuit) and the fault duration
would be such that the filter C would not be discharged to the zero line.
However, I do understand that a low Z long duration fault could allow the
zero point to be seen on the B+.
Maybe someone has observed B+ voltage during a tube flash-over, and can
comment and / or correct my thinking.
Seasons Greetings to all!
Jeff - K1LE - CT ><>
|