Re: MOTs and ballasting

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

Original poster: "Peter Terren by way of Terry Fritz <teslalist-at-qwest-dot-net>" <pterren-at-iinet-dot-net.au>

Steve, see comments below re 4 pack MOT's.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, April 19, 2003 11:12 PM
Subject: MOTs and ballasting


 > Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<srward16-at-hotmail-dot-com>
 >
 > I really hate to bring this topic up again, as im sure its been talked
 > about a lot.  But i think my case is slightly different.  Im working with
a
 > friend on a large twin coil.  We have 4 mots for a 5-6kva supply
 > (hopefully).  We have a 240V 50A line.  But, as one could imagine, the
 > ballast is going to be a pain to design.
snip
  >Any help on designing
 > a 5+kva MOT 4 pack is really needed.  Are there any sites that have done
 > what i need to do???  Oh, and we dont have a variac (i know, bad news).  I
 > do have a 280v 25A relay though, but its not a variac.

I don't use a ballast with my 4 pack MOT's and managed for a long time
without a variac. I have used smaller tank caps and a slower speed on my
ASRG if I needed to reduce the power. It peaks at over 20A (= 5 KVA) when
flat out but that may be fine on your 50 A line which is 12.5 KVA!  Just put
them in series and preferably under transformer oil particularly if running
at higher powers. If you need a simple ballast then 1 or two paralleled
2400W fan heaters is easy.

 > Oh, and has anyone used PFC on a mot supply?  I really hate to pull THAT
 > much current if i dont have to.  I think Java TC said something like 250uf
 > or something, will it really work though?  Ive used the PFC on my 2kva
 > coil, and it worked awesome, but that is with NSTs.
 > Steve Ward.

  I have about 30uF of PFC caps. I recently added 100uF but there was no
discernible difference in current draw or spark length somewhat
dissapointingly. I am sure a lot of people are not using them on pole pigs.
I am getting 6 foot sparks at present.
More info on http://members.iinet-dot-net.au/~pterren/ (Tesla Downunder)

Peter