Re: MOT Mods

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

Original poster: "tesla by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla-at-paradise-dot-net.nz>

Tnx for your insights.
Some comments
I am using 6 MOTS in 3 pairs with the secondaries in series (outer pairs in
oil)
The 50Hz resonant charging value is quite a lot larger than the MMC BUT if I
drive thru MWO caps and diodes clamps a (ie the classic AC couple and diode
clamp) the Input Mains current is very high. The Large capacitive load of
this is close enough to resonance to cancel out the most of the  9Hy of
output inductance of each MOT. My coil runs at about 15A mains current with
22mHy of ballast and partial PFC.

Yes the SRSG works very well to reduce mains current.
Your observation of  magnetic coupling coeff based on geometry was most
useful too. Because of duty cycle heatis not a problem for my coil.
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, May 09, 2001 4:53 PM
Subject: RE: MOT Mods


> Original poster: "Loudner, Godfrey by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <gloudner-at-SINTE.EDU>
>
> Hi Ted
>
> I took a look at some of my 41 MOTs, and I found the type you want to
> modify. After you remove the filament winding, there is a little bit of
> space to fill with extra shunting plates. Filling the extra space with
> shunting plates will not contribute much to the ability of the MOT to
limit
> current. Notice the tight combination of core and windings. This means
that
> the coupling coefficient of a MOT without shunts is close to 1. Adding a
> full deck of shunts across the core between the primary and secondary will
> reduce the coupling coefficient, but not enough to make the MOT run cool
for
> an extended period of time. Notice that the core of a NST is long. This
> means that the coupling coefficient of a NST without shunts is much less
> than 1. After Shunts are added, the coupling coefficient is reduced to a
> level where the NST can run cool for an extended period of time. I have
> knocked the shunts out of some MOTs, and noticed only a slight increase in
> current output. In fact most of the current limiting in a microwave oven
is
> performed by the capacitor that is connected in series with one of the
high
> voltage leads. You should continue using a ballast. I am assuming that you
> want to use a static spark gap in your tank circuit, and that you are not
> using a rectification bridge. Otherwise the capacitors in a bridge will
> contribute to current limiting, and playing at a rotary spark gap can play
a
> significant role in current limiting. Even if you are successful in making
a
> very current limited MOT, events can happen in a tank circuit that can
> overcome your current limiting efforts. Don't waste your time doing such
> surgery on your MOTs. My suggestion is to put two MOTs in series for