Re: MOT Powered Coil

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

Original poster: "J Whyte by way of Terry Fritz <twftesla-at-qwest-dot-net>" <xoom321-at-hotmail-dot-com>




>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: MOT Powered Coil
>Date: Sun, 13 Jan 2002 07:41:49 -0700
>
>Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><youngs-at-konnections-dot-net>
>
>Mark, see comments below:
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Saturday, January 12, 2002 5:12 PM
>Subject: Re: MOT Powered Coil
>
>
> > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><A123X-at-aol-dot-com>
> >
> > Will an MMC rated for 12Kvdc be enough for the twin MOT supply with an
>output
> > of 8Kvac or technically a round 11KVDC?
>ANSWER:  I believe Terry would say yes.  If it was me, I would feel more
>comfortable with at least a 15 KVDC MMC.
> >Also, if I used 4 MOT's in series how
> > much will it matter if some are kinda a bit smaller and the voltage 
>output
>of
> > them varies?
>ANSWER:  It will be OK.  The smaller one(s) may get a bit warmer under load
>than the others, but that's ok.
>
>It would seem to me that the large MOT's would put out more of the
> > power [ANSWER - usually true] and even if this isn't the case wouldn't 
>an
>1800v MOT put out more
> > current than the 2000v or 2100v ones causing things to get messed up? or
>do
> > things just even out?
>  > Mark
>
>ANSWER:  The 2000 or 2100 volt MOTs may put out more current if, for
>example, the 1800 volt model was for a 500 watt oven and the 2000+ ones 
>were
>from large or commercial ovens.  Whether more or less, it won't "mess up"
>things.  Most MOTs can put out more current than you need anyway for small
>and medium sized coils.
>
>Ideally, you would like 4 matched MOTs, but that is tough to find.  So just
>use what you have.
>
>Now I have a question about putting two MOTs in series.  Three ways of 
>doing
>it are 1) connect the secondary outside winding of MOT A to the core of MOT
>B.  This puts voltage stress between the MOT B primary and the core.  2)
>connect the secondary outside winding of MOT A to the inside winding
>(disconnected from the core) of MOT B and ground the core.  This puts
>voltage stress between the inside of of the MOT B secondary to the core.  
>3)
>(I have never heard of this being done) connect the outside winding of MOT 
>A
>to the disconnected inside winding of MOT B (same as 2), and use a high
>value resistor divider across MOT A to make the core of MOT B be about half
>the voltage of MOT A.  This would share the voltage stress between the MOT 
>B
>primary and inside winding of the secondary.
>
>Which method is most likely to avoid insulation breakdown in MOT B?  Anyone
>know the typical breakdown voltage of a MOT primary to the core as compared
>to a disconnected MOT secondary to the core?
>--Steve
-----------------------------------------------------------------------
OIL IS THE ANSWER! ....I have 4 **older** 2000 VA MUT's in series giving me 
~8 kVA (possiably 8.8 kVA) -at- a steady 16 kVAC....all under oil! I have had 
NO problems so far.I have all my MOT's seperated at least 2.5" from each 
other, and the whole set up is isolated above ground. The Core's remain HOT, 
but they are placed in an insulated container with heavy mineral oil. I have 
yet to run a Tesla Coil with it.

Without oil, MOT's get WAY too warm and the insulation breaks down -at- around 
6 kVAC.

I think mineral oil has an insulation factor of (30kV per .0314")....
anyone actually know???