Re: Polarized HV/ what's + and what's -

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

Original poster: "Peter Terren" <pterren1-at-iinet-dot-net.au> 

I have done experiments of my own with
my 100 KV DC supply.  For electrodes I used a needle point copper wire and a
5 cm brass sphere (well, a door knob actually).  The longest sparks were
with the needle as positive.  The readings that follow are spark lengths in
mm with
(needle pos:sphere pos and ratio).
15:12      1.25
53:41      1.29
100:53    1.88   ie  47% difference

Peter (Tesla Downunder)
http://tesladownunder.iinet-dot-net.au


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, August 07, 2004 11:34 PM
Subject: Polarized HV/ what's + and what's -


 > Original poster: "David Rieben" <drieben-at-midsouth.rr-dot-com>
 >
 > Hi all,
 >
 > I recently scored a pretty nice x-ray transformer. I think it's
 > rated around 150 kV -at- ~ 600 mA. I've already repaired a
 > carbon tracked phenolic rectifier mount twice. The new
 > phenolic mounting block also carbon tracked after the
 > first repair but so far the second repair has held up (keep-
 > ing my fingers crossed). Anyway, I'm wanting to keep
 > the rectifiers intact in this transformer since I'm wanting
 > this one as a very high DC voltage source. Since I have
 > it all back together after the last repair I really don't want
 > to dig into the oily mess again just to get a close look at
 > the diodes to determine the polarity of the HV outputs. I
 > have heard that one polarity tends to form corona easier
 > and actually arc further at a given voltage than the other.
 > I've noticed this phenomena from the output leads of this
 > transformer as I slowly ramp up the input voltage to it with
 > a big variac. Of course I'm also seriesing the variac's out-
 > put to it with a ballast assembly since x-ray trannies are
 > NOT current limited. Anyway, I was thinking that the ne-
 > gative terminal would be the one that would most likely
 > tend to more corona and arc further at a given voltage
 > but I simply can't remeber for sure. I think Antonio de
 > Quieros was talking about this once. Can anyone tell
 > me which polarity will form more corona and arc further
 > at a given DC voltage?
 >
 > Thanks,
 > David Rieben
 >
 >
 >
 >